Windows 7 & XP File Sharing

The facts:

- 36 PCs networked in our office
- 30 of the 36 have XP
- 6 of the 36 have Windows 7 (W7)

- every PC has a "Jobs" folder on their C: drive that is shared

- all 6 of the W7 PCs are able to share with every PC in the network

- all 30 of the XP PCs are able to share with only 4 of the 6 W7 PCs

- for some reason, 2 of the 6 W7 PCs are not accessible from the 30 XP PCs
- keep in mind that the all of the W7 PCs can read each other

Any suggestions?

Any help would be greatly appreciated!

Do they not show up at all?
This doesn't sound like a version incompatibility thing as most of the PCs can inter-operate.

Problem solved.

6 of 36 the PC stations in our office were upgraded to W7. At first all of the stations could read each others shared folders. Then periodically all of the XP stations could not be read a particular W7 station. It happened randomly with no reason.

The answer lies in the "Network and Sharing Center". Under the "Advanced sharing settings" you will find three profiles, "Home or Work", "Public" and "Domain". We are a domain. The settings for "Network discovery" and File and printer sharing" must be set to on, while "Public folder sharing" is off. For the other two profiles "Network discovery" and "Public folder sharing" must be off. The "Network discovery" should not matter, but in my findings it does. If either of those settings were on, network access ceased. So, either they were set that way from the beginning (I have no way of knowing) and it took some time for the connection to cease, or it just randomally changed on it own. Regardless, once I corrected the settings, the W7 PCs were again able to share with the XP PCs.

Thanks everyone for your suggestions!