I'm getting this in various places at Google Analytics:

<<An Error Has Been Detected

Please try again. If you are experiencing long delays, please reduce the selected date range or disable date comparison. Thank you for your patience.>>

Seems to be working for me. What sections are you getting it on?

Philipp
Even I get such error when the date range is too big
May be a timeout is occurring while fetching so much data

I'm not sure if same was the issue with you, but for me the error is only when i ask for a BIG range.

I used to get this quite a lot when they first launched the new interface:

http://blogoscoped.com/forum/95506.html#id95822

<< And I got this several times when I was only requesting one day's worth of data for traffic sources, so there's no way I could possibly have reduced my query. >>

Maybe they're at capacity again and need to add a few more servers...

I get this in different sections, like referrers for CoverBrowser.com, and it sometimes appears and sometimes doesn't...