Network connection jamming Calendar?

Over the past six months or so (under Mac OS 10.8.x), I have frequently found that the Calendar app gets stuck in the Spinning-Wheel-of-Death mode from which there is no escape but Force Quit.

As far as I can determine, this only occurs when my machine (a MacBook Air) has an active network connection, though not all network connections seem to produce this behavior. That is, Calendar works some of the time, but it gets stuck often enough to render it completely unreliable.

Like most folks, my active calendars are on iCloud; for obvious reasons, calendars local to my two Macs (I also use a Mac Mini) have no practical use, and I have long since stopped adding events to them. I do have one networked calendar supported at my workplace and not on iCloud. However, Calendar stopped working properly before I started using it, so it's highly unlikely the problem is specific to that calendar.

Again, this is an intermittent problem. One potential clue is that I have yet to experience the problem on my workplace's network; the jams only seem to occur when I'm offsite, either on my commercial provider at home or using some other wired or wifi access.

Has anyone else seen this?

Thanks