need help to solve slow logon issue

hi all,

the situation is that winxp machines in a domain environment are all experiencing slow logon issue.
after enter user name and pwd then hit enter, applying computer setting and personal settings are taking some time( still reasonable ) but after that, no icon no window is appearing on screen (only wallpaper is shown). in task manager, i can see userinit.exe is running. this will take some time untill explorer.exe loads.

i suspect that winxp is trying to access some network shares during userinit.exe
is there anyway to find out what network shares winxp is trying to access during userinit process? and along with time spent ?
is there any tools??

note: i want to know what network shares not what processes that are running during userinit.exe