Laptop acting really strange

Hi, so I have a pretty weird issue that I will try my best to describe. My laptop sometimes freezes or starts lagging for a bit and then some parts of windows I have open go invisible or parts of the desktop icons too, and the text style in my browser changes to this typewriter default font.
Sometimes closing some programs makes it go away but not always.
Also I get an error from my firewall every time this happens, but I get the error like 5-10 minutes after the lag happens.
I dont know if its like a memory issue, software, graphics or some kind of weird virus... anyway if somebody had experience with this Id appreciate some help.

By the way my laptop is: Acer Aspire, M Celeron 420 (1.6 Ghz), 1G RAM, some integrated Intel graphics card.
Running Win XP, with AVG antivir and COMODO firewall.

Thanks

 

Done.

Unfortunately I dont remember the error, but it sometimes also appears faded and sometimes you cant see it.

Yes I have sp2 and I got the latest update just now.

I have the latest version and updates and the diagnostics shows no problems with the installation.

 

Well actually a couple weeks ago I posted in the malware forum about another problem I had, it turned out to be a false alarm but I did all those steps and abri checked it and said everything was fine.
This is the thread Im talking about : http://forums.majorgeeks.com/showthread.php?p=1111904#post1111904

Should I do it again now or is it safe to assume malware isnt the issue? (I hope this isnt happening as a consequence of those programs I ran in the first place lol )

 

Yes, I dont recall having this problem before.

So I just got this again, I tried to take a ss but I got an error saying there isnt enough memory to preform this action .

Anyway the error is : " ERROR : Could not load C:/program files/comodo/firewall/cfpres.dll , please check if application installation folder has this file. Aborting application."

I disconnected the modem and restarted the firewall and it didnt show any error.

I looked for the file in question and it is there, but just in case I downloaded a new one from the comodo support forum.

Memtest didnt report any error and no problems in the device manager either.

Also isnt it odd that under blocked intrusion attempts in my firewall I get 0? I mean I have the firewall installed for over a month and with my old one I would get like one alert each day.

 

One thing I forgot is that I converted my FS from FAT32 to NTFS like a week ago, I cant really remember if I had this issue before, but I guess that could be a possible cause ?

Anyway thanks for the link, Im def gonna report the error in that forum.