Hello,
If you install Eclipse separately and run it without MyEclipse and then install the perforce plugin, and repeat your test where you enter the password and restart and try again, what happens? So basically can you try to repeat this whole process without MyEclipse installed/?
Also, could you have a co-worker try to iinstall MyEcilpse into their eclipse and just try to replicate the error. If both you can’t replicate it with vanilla eclipse and your co-worker can replicate it, then we will need to do further followup to determine the problem.
Lastly, do you have any entries that seem relevant in your eclipse error log? Window > Show View > PDE Runtime > Error log.
Thanks