This behavior can occur because under certain conditions a parameter is not checked properly during definition of an MS-DOS-based device. (The correct behavior is to return a STATUS_INVALID_PARAMETER status to the caller.) The Csrss.exe process terminates due to an access violation, and the STOP c000021a error occurs when certain system processes terminate.
To resolve this problem, obtain the latest service pack for Windows 2000. For additional information, click the following article number to view the article in theMicrosoft Knowledge Base:
260910 How to Obtain the Latest Windows 2000 Service Pack
Microsoft has confirmed that this is a problem in Microsoft Windows 2000. This problem was first corrected in Windows 2000 Service Pack 2.