Just to let you know, the problem has come and gone intermittently over the past week, but I have now gone 2-3 days without it happening. During this time, the PC has been left on for several hours doing large file copies. It looks as though, just as strangely as it first appeared, the problem has now dissapeared. I'll log this thread as "solved" but am afraid that I can't really say what caused the problem to go.....In the meantime, thanks for everyone's suggestions.
My Dell Inspiron 530S has recently started failing to reconnect to the network after a period of inactivity. This was triggered when I bought a new router (which I connect to by ethernet cable). HOwever, changing back t the old router (which never had the problem) didn't fix it. I can use the Windows diagnostics (usually requires a reset of the Network Adapter), but this is a bodge. It's running Vista Home premium. I have already tried the following: I've seen this issue posted so many times. Can anyone tell me: Thanks in anticipation  Colin
Can't reconnect to network after sleep - existing suggestions don't work