Damjan

I have installed server 2008 sbs. On the server is one program which is used by 5 users. At the start this program works ok. But after fev days this program works very slow. Like 10 times slower. I noticed that when only one person works on this program it works ok, but when there are two of them it slow down drasticly. I don't know why this happend after fev days. I did turn off firewall and antivirus program, but no changes. Can someone help me with this?