I have the same problem.
On more pcs with windows xp and vpn client 5.0.06.0110 pcf file looses all parameters, that is host, group name and password.
This problem does not always happen, on my pc I never had it, but more users report it.
Pcs don't hang.
Cisco writes in the bug toolkit that this problem was fixed (CSCso94244), but people continues to have this problem.