terminal server logon issue

hi,

we are using windows 2000 terminal server (sp2) (application mode)with citrix metaframe 1.8.

some times my users can not logon to terminal server. when they try to connect to terminal server, it connects to terminal server but instead of giving logon screen its just hang with blue screen.

there is no event in the event viewer. i try to stop and stop most of the services but it doesn’t work.

we check the process everything seems to be normal, cpu usage is around 10 % and we have 4gb of memory.

to solve this problem for time being i have to restart the server.

we did not make any changes or did not install any new software.

this problem is not frequent, but it happens atlest twice in a month.

if any one come accross this issue or know any thing about it pls. let me know.

Thanx in advance