a virus. help!

[poppie]

help me!
how can I delete file scredi.dll in system32 folder?
avast detect it as Win32:Downloader-CDZ [trj] but it can not delete.
in boot scan, avast also detect this file and i choose delete but when windows starts, avast detect and it still there!
any special ways to remove this file?

[Lisandro]

I suggest:

1. Clean your temporary files.
2. Schedule a boot time scanning with avast with archive scanning turned on. If avast does not detect it, you can try DrWeb CureIT! instead.
3. Use SUPERantispyware, MBAM or Spyware Terminator to scan for spywares and trojans. If any infection is detected, better and safer is send the file to Quarantine than to simple delete them.
4. Test your machine with anti-rootkit applications. I suggest avast! antirootkit or Trend Micro RootkitBuster.
5. Make a HijackThis log to post here or this analysis site. Or even submit the RunScanner log to to on-line analysis.
6. Disable System Restore and then reenable it again.
7. Immunize your system with SpywareBlaster.
8. Check if you have insecure applications with Secunia Software Inspector.