Sessions remaining active

Hi,
We are facing some strange problem. In one of our database
users will connect to db through one web based tool developed by one of our developer. According to him session shouldnt remain active for much time. But some users are connected from 19 and 16th FEB are still showing active. If you try to trace that session no trace is getting generated. If you try to see waht sql's they are running they also show 0 rows selected. some how i think this is a application problem. But my boss wants me to check if any thing wrong on db side. i dont know how to troubleshoot this problem also i believe this is not a database problem.

can some body help me on this or direct to where to look for.

Rgds
Parag

If you try to see what program they are unning it gives "dllhost.exe"
Does any body knows or in some kind of problem before.

Rgds
Parag