I know this is a long shot but is anyone experiencing problems with any Macs running OSX 10.6 accessing the internet over the last couple of days?

All was well and has been fine for years but after the holiday the Macs running 10.6 (10.8 ones are fine) can only access the internet for a few minutes and then stop resolving anything. Turning the proxy off gives you access for a few minutes and then it stops again. Turning it back on does the same thing!.

Really weird and if anyone can help I would appreciate it.