You have probably picked up something that is preventing this application from starting.
I'm currently running Adobe 7 Pro but I had 6 loaded on XP SP2 for a long time till I updated to 7.
If you don't have any Mal Ware Scanners loaded you can try these
Ad Aware
http://tinyurl.com/qoppr
Spy Bot S&D
http://tinyurl.com/yrwy2
Download and install both of these and then update them. Reboot as requested and when everything is fully updated reboot into [b]Safe Mode[/b] and run the Scans. I start off with Ad Aware and delete anything that it finds then run the scan again just to make sure that it actually removed what it claimed it did and that there was nothing hiding under what it picked up the first time. I continue running this till it comes up as clean which on a first time may be 6 or 7 scans.
Then run Spy Bot S&D but you have to be a bit careful here as there are some False Positives that can be thrown up things like Windows Defender and some Internet Banking Programs can be picked up as well as a lot of free ware that may be installed on some personal computers. If you want to keep these programs untick the boxes beside them and run the Repair Problems then when that is finished run the scan again just to make sure that it did remove what it said it did and that there is nothing else hiding under what it removed. Sometimes it will pick up stuff loaded into Memory and you'll need to allow it to scan the system on the next reboot to get rid of the infections.
Col