I have the exact same problem in Illustrator CS5 using Lion on my 2011 i7 iMac with 16gb memory whenever I'm saving over ethernet (or wifi) on my time capsule disk. No problems when saving to a local disk.
Funny thing is that my wife, Using CS5 for Windows 7 on her HP laptop, can work from the Time Capsule disk over the network in Illustrator CS5 no problem!!! So much for Mac being more stable and reliable then Windows.
I've updated the Time Capsule to 7.6 firmware yesterday (november 10th 2011) with no changes. Apple has been made aware of this problem in September!! It worked fine in Snow Leopard, so Apple seems to be to blame, not Adobe! All Software updates have been done, everything is up to date!
I switched to Apple with this enormously expensive i7 2011 iMac just so I wouldn't have these kinds of problems!!! I even bought the Time Capsule, which is a quite expensive router. My iPad and iPhones gave me a much better user experience. Come on Apple!
I've also had problems with bluetooth keyboards randomly refusing to pair, my Apogee Duet randomly refusing to pair! Excel refusing to open files from the Time Capsule. When I copied them using Finder to a local disk, I could open that same file no problem! I mean come on! All this expensive hardware and more problems than I had using Windows 7 last year!
I am disappointed and hope to hear about a solution soon from Apple!