It's generally not recommended to try running xpp or xpf files from a network share - as it puts XPression at the mercy of the network speed/connection quality. It's better practice to copy the file locally before trying to open them. However, XPression will work when used this way.
That said:
- do you have read/write to the network share?
- do you have UAC enabled?
- do you have a firewall or anti-virus enabled?
- did you add the XPression PC to a domain?
It is very likely some type of IT restriction.
#XPression