Right click on the file, and click on properties. Make sure that "Ready Only" box is
UNCHECKED. Go into Windows Explorer, and view your C: Drive. If that file is infected with a trojan, look to find the file linked in your autoexec.bat (C: Drive), win.ini (c:\windows), system.ini (c:\windows), startup folder(c:\windows\start menu\programs\startup), and system startup - can all be edited by opening up msconfig. If it shows up in any of those, remove it, and save.
Hit CTRL+ALT+DEL on your keyboard, and close all programs except for explorer.
Next. Open up notepad, copy and paste this:
Mystring = (80000000)
then click on save as, save as type "all files" and name it memory.vbs, save it anywhere you want. Double click on it, this will clear your memory.
Reboot. Then try to delete the file, if that fails, boot into real mode dos and delete it from there. After you dispose of this nasty, search in your registry (start-run-regedit) for the file to pop up, remove it.
You should be all set after that. However, I suggest you do a deep scan for viruses after just to double check it hadn't already spread. Cause you never know, a damn worm can still live when chopped up.