To remove Win32/Miuref.gen!A from your Windows Vista PC, you can follow the steps below:
Step 1: Restart your computer into Safe Mode with Networking
Restart your PC, as the computer is booting press and hold “F8 Key” on your
keyboard, which will bring up the “Windows Advanced Options Menu”.
Use Up-Down arrow keys from your keyboard to move to “Safe Mode with Networking” and
press your Enter key to go on.
Step 2: End running process
Right click on the taskbar and click “Start Task Manager”.
While Windows Task Manager appears, switch to its Processes tab, find out and click
End Process button block the processes related to this Trojan virus.
Step 3: Show hidden files and folders
Click on the Start button on the left corner of the screen and select Control Panel
from the Start menu list.
Click on Appearance and Personalization link.
Double-click Folder Options to open it.
Navigate to the View tab, select the radio button labeled Show hidden files, folders,
or drives and uncheck Hide protected operating system files (Recommended) at Advanced
Settings column. Then click OK to apply the change.
Step 4: Navigate to directory and delete all related files
Step 5: Clean up registry entries
Click “Start” button and go to “Run”, type “regedit” into the run box and press
the “Enter” key or “Ok” button to continue.
When the Registry Editor opens, search for the registry keys and delete all of them.
Step 6: Restart your machine
If you have any doubt, you can refer to this post:http://www.malwarefixnow.com/infected-by-win32miuref-gena-how-to-remove/