My configuration is as-follows: - Cable Modem - Sonicwall Firewall - Switch - 3 PowerMac G5s (10.5 on two, 10.4 on one) - 1 iMac (10.4+) - 1 Windows XP (w/ shared external Maxtor 250Gb drive) - 2 Networked printers Via the Macs, we've been accessing the external drive with no issues via the Network / Workgroups / PC_Name and also via a number of folder aliases we have established. We recently backed up lots of data to the external drive as we migrated to Leopard. Here are the odd occurrences that happened on the external drive that have me scratching my head. Duplicate folders appeared on the external drive. The existing is "folder" and the newly duplicated folders were created with an underscore (ie "_folder".) A folder called "private" and a sub folder called "tmp" were created. Inside tmp was a series of long alphanumberic file names for files that appeared to have CSS. Another folder was created and had something call the "mrtstub.exe" Here's reference... http://www.microsoft.com/communitie...&tid=c0b6f0d6-4894-4fe8-9ea2-82a6c4eee208&p=1 At this point, I'm convinced it's some Virus that's eventually going to eat up all my data. I deleted the Private and other folder with the .EXE and then downloaded, installed and ran TrendMicro's antivirus software.(http://us.trendmicro.com/us/home/). Unfortunately, it didn't get better... Today our Network window changes appearance. The Network no longer has Workgroups, Servers, etc. All shared computers are listed as aliases in the root of Network. The network printers became unaccessible from the G5s with Leopard, but fine on the others. All the Macs can no longer see or access the PC or its external drive. Anyone ever come across something like this? This set up has run great for the past 6 months. The latest change was an install of Leopard on two of the systems. I'm at a loss here... So, any thoughts, insight or even sympathy might help at this point.