Gnomie Greg Knightes wrote with this comment:

I recently had this problem. I newly reinstalled Windows XP Pro on my computer and the network was fine. I could see the other two computers; they could see mine. We could exchange files back and forth and I could use the printer connected to one of the other computers. After a few weeks, I could not access the printer from my computer. The other two computers could see mine and access files; I could ping the other two computers by name and address. I spent MONTHS troubleshooting! I scoured the net and the Microsoft Knowledge base, and I’ve reinstalled the networks. Nothing helped! I was at wit’s end!!

One day, I was trying various free spyware and anti-virus programs besides Ad-Aware and Spybot Search and Destroy. I must have tried five or six. They each found something that others missed.

A few days later I went to tackle the network problem again but, lo and behold, it was working!

Now, I scan more religiously with multiple programs and haven’t had any problems since!

I’d like to add that it’s been my experience that many, many problems and general wierdness on a PC are caused by spyware. If a customer complains to me about strange behaviour of their computer, I look for evidence of spyware first. If I find it, I remove it, and 95% of the time that cures the weirdness that my customer was complaining about.