Virus affected my computer startup

Hello,
Yesterday I used a pen drive to transfer some files from my Dell Vostro Laptop(Vista Basic) running with Microsoft Security Essentials. MSE detected few viruses and claimed to clean them. But when I accessed the drive I could still see some viruses; every folder had a .exe file of its own name. I again checked the drive with MSE but it detected nothing. Then I unplugged the drive from my PC and shut it down.

Next time when I booted my PC, a window appeared showing my Documents folder, and a black screen appeared when i minimized the window. The desktop and start menu were gone . I was able to access all the programs using task manager (CTRL+SHIFT+DEL). Then I started explorer.exe by clicking New Task and my PC started working normally. But when I again restarted the system, the problem persisted.

Then I uninstalled MSE and installed a trial version of Kaspersky. I scanned my computer with it but it showed nothing. Then I scanned the pen drive I used
previously and it detected 7 instances of "Trojan-Downloader.Win32.VB.hir" which KIS deleted successfully. I believe that this virus has altered my system registries.

Can any one help?

same type of thing happen to me i reinstalled vista and it seemed to still be working sluggish so i just took the damn thing back to bestbuy and they did tests on it and told me it was power supply and the motherboard. so only thing i can say is reinstall windows or take it to the store u bought it if u still have warranty.

Hi there, download and install Avast 5 beta anti virus and run a full scan. It should remove the viruses.