I’m about out of ideas, but you seem to keep getting infected/reinfected and it is probably down to not having your OS fully upto date. The very name RPCexploit indicates exploiting the Romote Procedure Call, a windows patch for this came out ages ago for this.

I did a search simply on Win32:RPCexploit and it returned 91 hits, this is just one. http://www.sophos.com/virusinfo/analyses/w32rpcspybota.html This may be of help, it also give a link to the MS patch.

Microsoft issued a patch for the vulnerability exploited by this worm on July 16, 2003. The patch is available from [url=http://www.microsoft.com/technet/security/bulletin/MS03-026.asp]www.microsoft.com/technet/security/bulletin/MS03-026.asp[/url].

If you haven’t got that patch installed you are going to keep getting infected.