Laptop experiences major lag on simple tasks

I see that another person had a similar issue in the recommended posts section - several year old laptop, slows to a crawl on simple things like MS word or streaming a youtube video while CPU usage shoots up to 100%, but no single task appears to be responsible. All attempts to reformat produce results that last for about 2 days, after which point it is painfully slow again. the model is a Compaq Presario A900.

I am completely new to the forums, so if there are any diagnostic logs you need me to post please let me know. I don't know much about malware, but it wouldn't surprise me if there was some - I had this laptop in university while in residence, and my roommates liked to screw with me by going on my laptop when I was out and hiding rude videos around my hard drive, which would be activated by a programmed schedule when I did a certain action. It was not uncommon for me to return with a meal to find 20 different gay pornography websites streaming at full volume.

In terms of heating issues, I have always been good to give my laptop the breathing space it needs, so I would be surprised if the heat level was an issue.

Thank you in advance for any help, I have sent my large gaming computer home to improve my study habits, so this little laptop is all I have.

 

My initial thoughts:

The HDD is having issues. Try downloading HDTune and looking for bad blocks, as well as doing a benchmark looking for massive drops in the transfer rate.

Windows Update is downloading and installing some kind of rubbish driver that is causing a piece of hardware to slow down. I frequently see Windows Update download the wrong Nvidia driver, which causes the computer to BSOD until you remove it and replace it with a proper version.

 

In addition to running tests on the HDD, hold your ear up to the fan area (or peek in the fan intake using a flashlight) to be sure the cooling fan is spinning properly.

If you have a can of compressed air around, it wouldn't hurt to clean both the fan intake and exhaust areas with it - be sure the PC is tuned off and has cooled down before doing this.

Excessive dust and/or a broken cooling fan will cause overheating. Initially this will slow down the PC; over time it can cause a meltdown of the CPU or onboard graphics.

Hope this helps.

 

Hey, thanks for the advice. I have downloaded HDD tuner but don't know what to make of the output. Any logs or pictures I can post that someone with more knowledge could explain to me?