Wow did this issue get under my skin.
At my current client, where their SharePoint 2010 Enterprise Intranet is about as business critical as a SP environment can be – I performed the SP1 and Aug 2011 CU updates. The updates themselves went about as smooth as could be expected, until we noticed that lists and libraries would give the generic error w/ correlation ID when navigating to the List Settings page (/_layouts/listedit.aspx).
This seemed like not too big of a deal on the first site collection we noticed it on – then we realized it was farm-wide.
After doing a lot of log-reading, re-running PSCONFIG.exe to ensure that everything completed from an upgrade perspective; we were in the dark…
This morning I noticed something while browsing through the layouts folder – listedit.aspx (and some other files) was modified on 6/8/2011 at 11:46 AM. Most of the other aspx files were showing a modified date much further in the past.
On a whim I copied listedit.aspx from a known-good farm into my broken farm and VOILA – lists and libraries work again.
This might not help anybody, because I couldn’t find anyone else having this exact issue – but I didn’t want to lose track of the “fix.”