This is tough because it happens to some computers and not others. First thing would be for all computers to be 4GBs and the server at least 8GB if not more. I haven't read all of this, but if you have Win 6 Pro 64-bit, as Sandeep says, you need more RAM. The recommendation for 32 is 1GB and 64 is 2GBs. Obviously, too small but just shows the difference.
Yes, I would definitely get a 1GB switch otherwise, you may as well be using Cat5, not even Cat5e. Make everything Gb.
You could make sure your page file is 1.5 times your RAM. This can make a large difference especially if you move it off your system drive, best if you have it on its own partition.
The problem with 4GB servers is it doesn't take long for SQL to become full. Eventually, you can even run out of RAM, and the server becomes slow. So, the reflex action is to reboot and get all that RAM back. But, in doing so, you lose the whole idea of how SQL works. That 1GB of RAM was 1GB of pages, queries that SQL learned AC liked. This allows AC to get its info from RAM and not the "hard drive" database. Much faster.
I think the most important thing to do (that very few people do even when it is suggested) is get everything out of the middle. Either connect the computer with a crossover cable (nowadays you can usually get away with play Ethernet) to the server. Or go to Best Buy and get a small four port 1GB Linksys switch and plug the computer via a Cat6 cable to the server. Now see how it performs. If it performs badly, it is the computer and you can put all your efforts there. If it works perfectly, then it is a networking issue.
