Need Help troubleshooting Computer Lag and Freezes

Hi for the last week or so i've been having major problems with my computer.
Running windows 7

Problems:
1. Computer is slow after log in and results in a hang about half the time. If it doesn't it will usually stay fine till the next time i reboot. My problems happen MOSTLY right after log in but not always (sometimes after hours of gaming).
2. When it hangs it seems to happen more when i am using a web browser, but it has happened when i have been playing games also. It doesn't seem to matter which browser i use ( safari, chrome, or IE).
3. When the pc starts to lag usually the browser becomes unresponsive first and i try to open task manager and it will freeze at the selection screen that pops up when u hit ctrl+alt+del saying something like "loading security protocols"
4. When i start task manager right away before any problems show up i don't see any obv process or services that are taking up alot of memory or cpu usage.
5. VERY often after a freeze my computer will then hang during boot at "verifying dmi processes" or something (sorry i can't rmmber exactly atm). I find that this is often because the boot order of my hard drives has changed. This happened a lot till I saved the correct boot order as the default boot order in case of errors. Now usually it does not get stuck at "verifying dmi processes", but it still happens sometimes! Once, my main hard drive, which is an ssd, even disappeared from my hard drive list in bios after a freeze.
6. The web browser problem started happening after i got a virus which i removed with malwarebytes. I use windows security essentials as my virus protection and firewall and the free version of malwarebytes to supplement that. During the virus problem my windows security essentials became off and i couldnt turn it on. after running malwarebytes and removing the virus i reinstalled security essentials and everything seems fine ( scans by both programs show no problems).

#6 mite be the cause of everything but because i've been having the problems of #5 consistently from way before the rest of the problems i suspect a hardware issue is the root cause.

How can i trouble shoot my computer hardware to figure out what is causing the problem? Any help is greatly appreciated. Thanks!

 

Sorry i Edited my post but i didn't know about the 10 minute limit.
Edited***
Hi for the last week or so i've been having major problems with my computer.
Running windows 7

Problems:
1. Computer is slow after log in and results in a hang about half the time. If it doesn't it will usually stay fine till the next time i reboot. My problems happen MOSTLY right after log in, but not always (sometimes after hours of gaming), OR when using my browser. Often it will freeze repeatedly reboot after reboot.
2. When it hangs it seems to happen more when i am using a web browser, but it has happened when i have been playing games also. It doesn't seem to matter which browser i use ( safari, chrome, or IE). Now i try to never use my browser and i can usually play games without any problems if i get past the log in. I think i should note that a couple days ago i find that all my Chrome settings had been mysteriously reset and all my bookmarks and such were gone ( unfortunately im not sure if this happened directly after a freeze.
3. When the pc starts to lag usually the browser becomes unresponsive first and i try to open task manager and it will freeze at the selection screen that pops up when u hit ctrl+alt+del saying something like "loading security protocols". If i don't do anything at all after i sense the lag it either eventually goes away, or the computer completely freezes.
4. When i start task manager right away as soon as i log in before any problems show up i don't see any obv process or services that are taking up alot of memory or cpu usage when i start to lag. For example i leave task manager open and when my browser starts to lag or while i'm gaming my game freezes, BEFORE the freeze (or sometimes bluescreen) i can still look through task manager for a couple seconds but my cpu and memory usage is at a low percentage.
5. VERY often after a freeze my computer will then hang during boot at "verifying dmi processes" or something (sorry i can't rmmber exactly atm). I find that this is often because the boot order of my hard drives has changed. This happened a lot till I saved the correct boot order as the default boot order in case of errors. Now usually it does not get stuck at "verifying dmi processes", but it still happens sometimes! Sometimes, my main hard drive, which is an ssd, even disappeared from my hard drive list in bios after a freeze (this is fixed usually after a reboot).
6. The web browser problem started happening after i got a virus which i removed with malwarebytes. I use windows security essentials as my virus protection and firewall and the free version of malwarebytes to supplement that. During the virus problem my windows security essentials became off and i couldnt turn it on. after running malwarebytes and removing the virus i reinstalled security essentials and everything seems fine ( scans by both programs show no problems).

#6 mite be the cause of everything but because i've been having the problems of #5 consistently from way before the rest of the problems i suspect a hardware issue is the root cause. I'd also like to note that my computer temperatures are all fine, cpu and gpu's running at normal temps.

How can i trouble shoot my computer hardware to figure out what is causing the problem? Any help is greatly appreciated. Thanks!