Stop Me From Pulling All My Hair Out!

I sure hope I don't go bald before I get some real help with understanding what's going on with my PC! It's a Toshiba Satellite A205 laptop with a Vista/32-bit OS. I've had it several years and it's worked flawlessly. However, a few months ago (July), I started experiencing an assortment of problems such as text jumping in the navigation bar;loss of cookies; pages jumping left upon opening and inability to center them; inability to make menu selections with a mouse and more. I first encountered these problems with Firefox but ran into the same issues with Google Chrome. However, when I switched over to IE8, the system seemed to work "normally" (or as well as any browser works with Explorer, that is). BUT, now it looks like I'm starting to have problems with IE as well.

So far, I've tried complete system scans with Windows One Live Care and have found nothing. Then, when my One Care subscription expired , I downloaded a free trial of ZoneAlarm and ran a complete system scan - again no virus or spyware was found. Yesterday, I uninstalled ZoneAlarm and downloaded Microsoft Essentials. Once again . . . no virus or spyware found. Yet, all the virus-like problems remain on my system!

In trying to ratchet up my search for a remedy,I tried to download the trial version of Malwarebytes tonight. Guess what? I'm able to download it alright. But when it comes to choosing the language for installation -- I am only able to select Chinese!!!! Not only can I not make the menu selection with my mouse, but even when I manually choose "English" from the menu list, the menu bar automatically switches over to Chinese each and every time!

I give up. Please help me before I pull the last lock of hair out of my already-graying head!

Thanks!