Boot error message

I administer a network concisting of a Win NT4 Server / Workstations. The workstations all have SP6a installed but 1 of the workstations has just started to come up with an error message only when the boot process has finished and the Ctrl,Alt,Del screen comes up. The message says: spoolss.exe – ordinal not found
the ordinal 6451 could not be located in the Dynamic Link Layer mfc42u.dll

I have tried to reinstall the latest service pack, but it doesn’t work, please help.

Mark