XP laptop no longer sees other PCs on network

[mhl]

I have a network consisting of 2 XP Pro desktop PCs, an XP Pro laptop and a NAS drive for storage. They connect through a Netgear router, the laptop wirelessly. Initially everything worked fine. Lately, however, the laptop has been unable to see desktop #2 and today it can no longer see desktop #1 either - although it can still see and connect to the NAS drive and the internet.

I don't know if it is just coincidence but I had the laptop connected to a different wireless network yesterday while travelling - although the fact remains that it can see my home network OK, just not two of the devices on it.

Any suggestions how to fix things?

Edit - have now connected laptop to network via RJ45 / Cat5 cable - and it still cannot see the two desktop PCs.