iPod Touch Connectivity Problems

We're using 6 2nd gen iPod touch on 3.0 in a workshop environment. There is two access points and we're using static IPs.

We're having a problem where they will work fine for a period of time but eventually the iPods won't go out to the internet and we get the error message - Server cannot be found. They are showing full reception on the wireless. There is no problems with the website they are trying to go to. The only way to cure it is to turn off the device and back on again several times till it works again. There are also laptops on the same network which we never have problems with which is what makes me think it must be something to do with the iPods.

We've tried installing Keepawake (to stop the wireless on the devices going into power save mode) as we suspected that the sleep mode was causing us problems. This seems to have helped but hasn't completely solved the problems.

Just to reiterate the problem isn't with connecting to the wireless but with going out to the internet (or thats how it seems)

I hope I've included enough info in this and I look forward to any responses.

Cheers