请教：TortoiseCVS 下载文件的历史版本出错。。。

idragonet

In C:\DOCUME~1\IDRAGO~1\LOCALS~1\Temp\TCV10658.tmp: "C:\Program
Files\CVSNT\cvs.exe" -q checkout -r 1.1 -d temp cb_sh.pbl
CVSROOT=

cvs checkout: CVSROOT is set but empty!  Make sure that the
cvs checkout: specification of CVSROOT is legal, either via the
cvs checkout: `-d' option, the CVSROOT environment variable, or the
cvs [checkout aborted]: CVS/Root file (if any).

Error, CVS operation failed