To check the registry key and change it if necessary:
1. Click Start>Run.
2. Type regedit and then click OK.
3. Navigate to the following key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Filesystem
4. In the right hand pane, right-click the following value, and then click Modify:
NtfsDisable8dot3NameCreation
5. Change the number in the Value data box to: 0
Please note that this is a DWORD value, not a String or Binary value.
6. Click OK.
7. Click Registry, and then click Exit.
Note you can save the registry key first by:
On the File menu, click Export.
In the File name box, type SaveKey, and then click Save.
Or create a system restore point prior to editing.
http://support.microsoft.com/default.aspx?scid=kb;EN-US;322756
HOW TO: Back Up, Edit, and Restore the Registry in Windows XP
Disclaimer: Modifying the registry can cause serious problems that may require you to
reinstall your operating system. Use the information provided at your own risk.