we run homogenous network based on Windows SBS (2008R2) server and W7 as clients. Today, the network start to act weird. From some of the computers (it seems that only from those who have been turned off during weekend) the speed of download from server shared drive is ridiculous, some 100-200kb/s on 1Gb network. From other computers the speed is just fine. What makes me crazy is the fact, that when I connect from the "slow" computer to the server via Remote desktop, and I simply COPY-PASTE the very same files to local computer, it runs with full speed (it means the physical connection between server and client is just fine and able to run on full speed, there is just some difference between copying from shared folder and via remote desktop) ! Ping behaves normally, all below 1ms, no timeouts, no lost packets.
All the clients and the server are 1Gb cable connected to Cisco SG-200 switch, no extra settings there. Only IPv4 is used, DNS and DHCP provided by Windows. Browsing on web on "slow" computers run on full speed as well, only shared drives and some applications from our server (photo map tiles) run slow.
I tried all I can, reseting network settings, setting various duplex mode on network cards, copy-paste various files, restarting services on server, disable and even uninstall antivirus, firewall, monitor on server and on client, that the network is not utilised (both run below 1%), the disks are not utilised (same ), CPU is just fine, so there are no visible problems on both sides, and as I mentioned, there are computers which can access the server with full speed, without anything being different.
Do you have ANY hints or ideas, how to troubleshoot it or what might be going wrong in this ?