Missing printers: pending deletion / deleted

Hi,
I have a strange random problem with ndps printer dissapearing.
The configuration is as follows:
Network printers asre assiciated with groups; Each each group adds/install
one printer. There are no groups removing printers!
Users are members of above groups.

Workstations: XP Prof ENG SP2, Novell client 4.91 sp1 (sp2 on some test
workstations but behaviour seems to be the same).

Users A logs in (he is in printing group groupA which adds printerA) but no
change in printers list.
In event log I can see two "Print" events:

1) PrinterA is pending deletion
2) PrinterA was deleted.

There is NO RULE in NONE of the groups to remove printers. Why this is
happening? Does anybody have similar problems?

This happens randomly on random users, random machines and random printers.
I haven't fount any logical plot in the observer behaviour.

Thank you,
Maja