I get a problem everytime I use Pro/E 2001 on my computer (win xp pro)... I start the program, it runs for a time, and then it freezes. I can continue to click, the program will do the actions (like saving) but with a lot of seconds between each one. All my friends are using those versions of Pro/E and Windows without any problem, so is there a well-known conflict between Pro/E and a spécific program, like ZoneAlarm or PhotoShop, for example?
Pro/e is a heavily networked or network aware program. I'm on a high speed network, through a cable internet modem. For protection, I've installed a fire wall. If I set the fire wall to block all transmission, Pro/e will start and seem to run normally for a while. But after some time, maybe 10-15 minutes, it will do as you've noticed, slow way down, and start to do a tremendous amount of data swapping to disk. If I have a resource meter running at the same time, I notice ram is maxed out. If I restore Pro/e's access to the network, it runs normally. Pro/e has four modules ~ xtop.exe, pro_comm_msg.exe, nmsd.exe and nmsq.exe ~ which request access to the network and open ports. Judging by running NETSTAT, the ports connect one module to another through the network. I'm guessing that, without network access, and when ram is maxed out, these modules start communicating through the hard drive.
Therefore, I'd investigate what your network situation is. Do you even have a network card. If you just have a card it helps and have the network support installed and activated. Also, try running NETSTAT while Pro/e is running to see if it has opened ports, all local and ephemeral TCP ports. Beyond that, Pro/e need a lot of ram, the more the merrier. But investigate the network issues first, including among your friends.