Can't PING Vista PC, but it can see other PCs on network

[Island_Boy_77]

Got hit with a virus for 1st time in a long, long time - that's what I get for seeing what it's like surfing without an AV!

Anyway, after cleaning up the mess (which was largely confined to the Trojan deleting a bunch of services and screwing with various security settings), I'm left with one nagging problem: I can see other PCs on my home network, and they can see me, but whenever they try to access my PC they get the good old "access denied". Further, when PING my PC from any of the other PCs, the PING just times out.

I've gone through all the usual stuff like resetting the firewall, running Combofix & SmitFraud (as well as Spybot & MalwareBytes), I've tried with firewall off and on, I've tried with MSE AV switched on & off, I've tried sharing the root of C: for "everyone" with full access - nada.

Let me be clear here: format / reload is out of the question. It's a 2-day process for me and I simply don't have the time or inclination to do it right now. The next format / reload will be to W7, and that only when I have a totally free weekend. So, there must be a fix for this sharing problem. I'm running Vista Business with SP2. All services appear to be running normally. All Windows updates done & checked. I did reinstall the .NET framework to try to fix this error:
The Net.Tcp Listener Adapter service depends on the Net.Tcp Port Sharing Service service which failed to start because of the following error:
The service cannot be started, either because it is disabled or because it has no enabled devices associated with it.

But although the reinstall (after using the .NET cleanup tool) was good, the error persists. Checking back through the logs, the error only showed up after the infection, so possibly there is a correlation with it all.

Additionally, I just found that while I can sync the computer with various servers using the manual w32 command-line, I can't sync the time via the control panel. I do have a full backup of the Registry from Sunday, but have not done a Registry restore on this scale before.