Problem with JTAG server on Quartus 4.0 for XP

Hello,

I'am trying to use Quartus II and NIOS II sdk for teaching and I'm 
facing a problem with the JTAG server service on the XP machines that 
are used by our students. Whenever a user logs in the JTAG server 
service systematically fails to launch automatically and reports an 
"error code 0".

The only way to make sure the JTAG service is launched correctly is to 
log in as an administrator and launch it manually from the service 
dialog box, but of course as soon as the administrator logs off, the 
problem arise again.

Since we use Quartus II in Digital Design classes, we obviously cannot 
afford to let the student work on machine as an administrator, and I am 
hence looking for some people who would have had similar problems.

PS : strangely, we did no had such problems with Quartus II 3.xx, 
however since we plan to use the nios II intensively, we need V4.1.


Thank you in advance,

Steven Derrien