I ran into this with a Linux box in a MSFT shop. Was using smbmount to mount shares from Windows boxen. Found that I could only connect a certain number of shares per box.... Turns out that there's this ten-user limit... and that each connection to a box (some had more than ten shares) counted as a concurrency.

My interim fix was to use autofs with a four second timeout (could have dropped this to 1-2 seconds, hmm...), which kept me from holding open any one connection too long, though I'd not time out if I was repeatedly hitting a share.

There's some additional stuff, including the opportunity to permanently authenticate to an NT domain, which may get around some of these restrictions. You're still limited by the number of simultaneous users accessing a share (or server), I suspect. Check with the Windows Boi, Peter Whysall, for specifics.