May be the error was not related at all to the virus but the fact that I performed a thorough scan and included drive a: which had no disk.
Anyway, yesterday night I run Spybot seach and I succeed to delete the virus. I could do it only by using Spybot while startin up the computer. Avast could not deal with it but the combination of the two did it (at least today I did not get any error messages).

Thanks anyway!

Elij