mapped network drive speed drops after some time

I have a problem with the speed of my mapped network drive.
At first al is wel and file loading is as fast as to be expected. But after some time the transfer speed drops dramaticaly and it becomes very slow. I tested it primaraly with loading of image sequences, but it affects all file loading the same.
If I logoff and login to windows again the speed is back to its full potential. And then after some time again it drops.
I have seached the internet for similar ploblems, but could not find this kind of problem, only the dropping of the connection entirely, but thats not the case here.

All user PC's that have the network drive mapped are windows7 Pro PC's with gigabit lan.
The server PC is also windows7 with quad gigabit lan, teamed to 1 connection. A 4 ssd raid setup via a MSI megaRaid controller provides the drive for mapping.
The switch is a HP proCurve 1810G-24.
Jumbo frames is disabled on all devices.
Because i have no domain, the password protection for file sharing on the server is disabled, so al user PC's can connect to the mapped network drive with their own username.

Is there some sort of idle timer on the mapped network drive that could be responsible or something?

Thanks in advance,

Jean-Paul

You probably have too many files in your network, which can corrupt the speed of your network drive. Try to take out some files put it on another folder, and separably map the network drive. See if the speed goes up. If it's not the case, then you probably got a virus in your network, just scan your computer with your anti-virus.

Hope it helps,
Best Regards
ITSS10