Network One PC can connect to the other but the other can't?

[ssmacc]

This is driving me nuts! The PC downstairs (DRPC) can connect to my PC upstairs (BRPC), but not vice-versa, I've tried all the "usual" settings but nothing has got the connection working, for a long time I could connect to shared folders on DRPC but not see it on the Network, now I can see on the Network but can't connect! (The network path was not found) and can not connect to the shared drive...

Any Ideas?

 

[Buffalo2102]

Have you recently done any upgrades or updates?

 

[ssmacc]

Not that I'm, aware of...it's just so hit and miss...mapped drives will connect one boot, the next nothing...wish I could explain it better bit there doesn't appear to be any pattern...