OSX 10.9 compatibility with Windows Small Business Server 2011?

Hi

I'm hoping someone here may be able to help me as our external server guys have been particularly unhelpful!

I'm the only Mac on a Windows server, which has recently been upgraded (??) to Windows Small Business Server 2011. I've recenty upgraded the work iMac to 10.9, but ever since the server change, I'm having intermittent dificulties saving files. Often, I get and error saying the file cannot be saved as I don't have permission to access the folder - which then worryingly REMOVES the file I'm trying to overwrite WITHOUT WARNING.

If I'm using Photoshop save for web, I get errors when clicking 'Save' to say that it can't, but does save the file, plus a second with a gibberish file name.

Most worryingly though, is that now on two occasions caused the iMac to crash and shutdown immediately, which is not good at all. Once was moving a file to overwrite another in the Finder, the second (today) was saving from Illustrator.

I'd noticed weird things with our old 2003 server before the switch and when I was still on 10.6 - mainly that my iMac was slow when connected (Adobe apps etc opened in a flash when unconnected, but took minutes when plugged in), but now I'm on 10.9 and the new server installed, these saving issues have arisen. (I ended up wiping the Mac and completely reinstalling everything to cure that slowness issue - never did find out what it was!).

The server guys are adamant that this has nothing to do with the server, and is all linked to my iMac - personally I'm not so sure, but I'm asking here to see if anyone else has had issues? It seems like some kind of permission problem? Do I need any special network settings for it to play nicely with the Windows server? My internet, email all goes through it, and I use it to store my work, but I'm not linked to any other server software in any way.

If anyone may have any clues to help I'd be really grateful!

Many thanks!

Ben