nal not showing up everytime

All,

Have a issue with a building, nw 6.5 sp6, zen 3(just started, unsure what specific version but its working fine in other buildings). XP SP2 on desktops.

Nal has for the last few weeks (one of those no one is sure when it started) been sporadic at best. Some machines need rebooted 3 times before nal will launch. Other times they will go a week and it will launch the first time everytime.

It isn't specific to one person, nor one machine. All machines in the building are the same model and imaged with the same image, little to any variation between them for extra software installed.

DS reports its happy. Server owns r/w copies of the proper partitions.

Any thoughts or questions?

thanks

Mike