VPN: Drive mapping issue (v12 and v13)

I've received some user complaints regarding the inability to map a drive over VPN. When I test using a Win 7 laptop over DSL I can map the drive and see the subfolder beneath it, but cannot open that subfolder to get to anything inside of it (sub-subfolders you might say). When I try opening the folder there's a pause and then an error pop-up window that says the folder's not accessible and, "The network path was not found."

This happens using the VPN on both v13.1.1 (build 0.0.4) and v12.1.3.6 (build 0.0.3, point release 6) F5s. However, when I connect to my lab VPN v14.0.0.2 (build 0.0.2 point release 2) it works fine. The VPN vserver and network access configs match between the v13 and v14 builds, but the lease pool is different between the v14 and v12/v13 VPNs. Until I move the lab VPN to its own VE F5 (it's sharing with other apps now) I cannot add that prod lease pool network to test it.

Has anyone dealt with this before? Any ideas? Thanks!