I have done extensive troubleshooting on this problem. Apple even replaced my Time Capsule. Replacing the Time Capsule made no difference at all.
I have downgraded all the way back to 7.5.1 firmware - done factory resets and reconfigured the Time Capsule in all of its possible configurations - with no difference in the behavior of the popup.
The problem (based on my testing and observations over a long period of time) may be contributed to - but not necessarily directly caused by the 7.6 and later firmware.
If I install Snow Leopard 10.6.3 or 10.6.4 (without doing any updates) - I do not get the popup - rather my AFP share quietly disconnects wtih no popup warning of any kind. I simply have to reconnect it. Somewhere in between Snow Leopard 10.6.5 and 10.6.8 - the popup started to appear - and somewhere around 10.6.8 - the 7.6 firmware upgrade became available. I believe the combination of 10.6.8 and the 7.6 firmware is causing the popup - the Time Capsule is causing the Mac to think it has disconnected (and maybe it actually does disconnect for a fraction of a second) - but as of 10.6.8 - this lost connection is very accuratly detected by the the OS and the popup appears. It does seem that by the time you even notice (or can respond to) the popup - the connection has re-established itself.
I only get the popup (in 10.6.8 and later) or the share quietly disconnects (in 10.6.4 and earlier) - when I have the TC mounted in finder (via AFP) - and I have either written or read a very large amount of data to the TC. By "large" I mean multiple gigabytes (such as copying an entire iTunes or iPhoto folder (or both of them)) to the drive. The copies are always successful - but usually a few minutes after the copy completes - the popup will appear saying that the drive has disconnected. If I don't do anything with the popup - I can still access the share and nothing appears to be wrong - however - at regular intervals following the initial appearance of the popup - the popup will reappear - even when the Time Capsule is just sitting there idle. This behavior repeats for anywhere for 4 to 8 more hours - at which point the popup ceases to appear - or until the share is unmounted.
If I mount the share specifically via SMB (via go connect to server smb://address of TC) I can copy data and leave the share connected for days - without any popup appearing. This is assuming that the data being copied is data that can be successfully copied via SMB and does not have any AFP dependencies.
It is almost as if when copying large amounts of data over AFP to the Time Capsule - that some threshhold is being set where maybe a flag within the OS is being set to indicate possible incompleteness of the copy operation or somehow it is incorrectly flagging a problem that it feels it needs to report to the user. In any case - I believe it is erroneous and some type of flag is not being reset when the copy completes successfully.
One thing I have not tried - is to copy a large amount of data - and then immediately copy a small amount of data before the popup has a chance to appear. I might try this and report back.
Also - Time Machine never seems to produce the popup - because Time Machine mounts the share via AFP - only when a backup is required - it then copies large amounts of data to the TC - and then immediately disconnects the AFP share - before the condition that causes the popup has a chance to appear.
If one were only to use the TC for Time Machine backups - then one would not ever see this error/warning. Is this possibly also a bug in the implementation of the AFP protocol as of Snow Leopard 10.6.8?
Is anybody else seeing the exact behavior that I have described here and under the same conditions?
Message was edited by: SBeattie2 - Corrected typo's in version numbers.