When you Google for the DCOM 10005 error, many entries can be found. The problem is that there is no single cause, no single remedy. In such case I would advise a wide spectrum repair process, hoping to eliminate the problem even without knowing the source.
Run XP repair installation. You can use my link below to G2G repair guide. Please note: XP repair does not always succeed and can even create other problems. To increase your chance for success please disconnect from your modem/router, boot to safe mode (your only option) and uninstall your AVG, zoneAlarm and any other antimalware program that is running in the background. Run disc cleaner and disk defragmantation. Run XP repair.
Even better still, answer my questions in the first paragraph and let's wait and see somewhat. Maybe other people will have better ideas. I honestly don't like XP repair.