It may be a coincidence that the freezing has started after a malware attack but are you aware that some malware is so deep rooted in the HDD that not even a full NTFS format will eradicate it, I mention this as you may need the assistance of the experts over on the malware forums.
Common causes of freeing are overheating and a poor power supply so I suggest checking them first, when was the last time that the case was cleaned out of heat trapping dust.
and install it. Once it's installed, run the program and post here the information it shows. The information I want you to post is the stuff that is circled in the example picture I have attached.
If you are running on a vista machine, please go to where you installed the program and run the program as administrator. (this is a screenshot from a vista machine)
To capture and post a screenshot;
Click on the ALT key + PRT SCR key..its on the top row..right hand side..now click on start...all programs...accessories...paint....left click in the white area ...press CTRL + V...click on file...click on save...save it to your desktop...name it something related to the screen your capturing... BE SURE TO SAVE IT AS A .JPG ...otherwise it may be to big to upload... then after typing in any response you have... click on browse...desktop...find the screenshot..select it and click on the upload button...then on the lower left...after it says upload successful...click on add reply like you normally would.
Depending on the results we may need to run further software for comparison.Screenshot instructions are provided to assist those that may read this topic but are not yet aware of the “how to”.