Windows 7: Flaky write access to server drive in company network

hi everyone,

i've been struggling for a while with an issue of writing files to a network drive in a small company (with no IT guy). I am not regular employee there, so I use my machine. There is a server with several shared drives, one of which is my problem (I don't have access and don't care about others). The problem is that I cannot write files to that drive. It tries, but for some reason (and only when using Windows 7) write speed is terribly low and only few small files eventually get saved. anything larger is next to hopeless. reading from drive works like a charm. Using same user name and password when running any other machine is no problem (all are XP Pro and few are Vista 64). The only machine where this problem exists is one with Windows 7 Home Pro 64. I would imagine that if the issue was user account related permissions) then same problem would exist on other (older) machines I used. I tried updating everything on my end, reinstalling Windows 7 from scratch (using new HDD), updating all drivers, etc. same problem. Current workaround is to burn data on DVDs or save them to 3.5" USB drive and then using another machine to copy files to server. this is tedious and slow as files are often large (dozens of 2-3Gb files)

Any idea on what can be tried to resolve this would be greatly appreciated.