Windows workgroup problem

I have a Windows workgroup (3 Win 7s and one Win 8) that has operated for several years with minimal problems. But two days ago my workhorse Win 7 PC was suddenly unrecognised by the other three PCs. It also ceased to be listed by my four PVRs. The frustrating thing is that the 'missing' PC can still see the other PCs, which means that the workgroup is still partially intact.

I saw this sort of thing in the early stages of the workgroup but things quickly settled down.

The frustration is that the 'tools' supplied by Microsoft to investigate networking problems are no help at all. One would think that the programmers would have included a proper tool to refresh workgroups.

I can work around the situation when working with my PCs but the situation with my PVRs is that I can no longer use my main PC as the source of AV files and have to use another PC instead.

All would be right again if there was full recognition among my PCs and my main PC was listed on my PVRs.

I know that I fixed this sort of thing in the past, but nothing I have tried as yet has been effective.

I am hoping that someone can help me get back on track.

Try a System Restore in the problem PC to a date prior to the issue?
Can you reach the problem PC from others with it's IP address?

Thanks, GokAy

No recent System Restore point available unfortunately.

Pinging from another PC unsuccessful.

Meanwhile the 'missing' PC can still see the other three PCs.

But I have to reinstall TeamViewer each reboot in order to get it working.

Windows Diagnostic Diagnostics is pathetic. All it can come up with is a suggestion that I contact my network administrator. Hey, that's me and I haven't got a clue.

I am wondering if I should try cancelling the workgroup on each PC and creating a new workgroup with a different name.

Are you running any security software on that PC that may be interfering?
Try a clean startup Troubleshoot Application Conflicts by Performing a Clean Startup
Do you have some software that does virtualization?

Can you post the zip file from Blue Screen of Death (BSOD) Posting Instructions please even though yours is not a BSOD.

You can also try running Tweaking.com - Windows Repair

I thought that I had seen everything that can happen in computing.

I got up this morning to find that the situation I have described was still happening, for the third day in a row. Did a few things I needed to do and then thought that I would have one more try on my Win 8 laptop (which is in the same room) to connect with my Win 7 all-in-one. There it was, as if the past two days hadn't happened. Tried to open TeamViewer on the Win 7 PC and there it was as well, after failing earlier. I went into the lounge and scanned for PCs on my PVR. Up popped the 'missing' PC. I had done nothing as far as I could determine.

Sorry to have bothered you but Windows PCs do seem to have a mind of their own. Of course, I am assuming that the situation will remain intact.

Good to hear it has been resolved (for now at least). If it happens again see post #4.