I had proe2000i, on my Windows 98 machine. It got a virus and I had to wipe the hard disk. My machine now runs on Windows 2000, but now my proe 2000i installs, but does not run.
Make sure you installed FlexLM license management with the 2000i install, and read in the license file you got from PTC. FlexLM works a little different on Win2K that 98. 2000i will run fine on Win2k. You will notice a jump in system performance with the new operating system.