Some programs work fine (like Firefox) even if I have opened them using Task Manager. Fearing that a virus/malware may have caused this, I tried running Malwarebytes, but nothing came up. My system apparently doesn't have a restore point, so System Restore would be useless. Weird thing is, CMD is telling me that I should be an admin to run /sfc scannow, even though the account I am using is an admin account.
I've tried almost every solution I came across online, but nothing worked.
My laptop is running on dual boot (Vista and XP) the Windows Explorer in Vista is the one that's been acting up. I tried rebooting to XP, and it worked. I scanned the Vista partition with Avira AntiVir while on XP. My Vista's explorer.exe in the winsxs folder is infected with a TR/Trash.Gen trojan. Earlier scans while on Vista did not show this, so I'm really stumped.
I'd quarantine my explorer.exe as per Avira's instructions, but I don't know what'll happen afterwards. So before I do anything stupid, I need advice.
Thanks.

Screenshot of Avira scan.