User Error Message Problem

Whenever I log into my Win 2K Pro box, I get this message:

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Windows cannot load the user’s profile but has logged you on with the default profile for the system.

DETAIL – Not enough storage is available to process this command.
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After I click “OK”, the system goes to the desktop normally. It’s not because of a lack of physical memory, because the machine has 1 GB of RAM. Any ideas?