I've read in an german forum, that their seems to be a problem with the dock.plist file which seems to be corrupted. So a solution seems to be
Translated the solution is:
Just delete the file com.apple.Dock.plist located in ~/Library/Preferences/ and restart.
But warning: your dock will be reseted (so your have to assembly your icons in the dock again) and also all related configurations you can make in the system preference dock dialog.
I had similar problems for about 18 months on my first generation Intel iMac until about a year ago - in my case it didn't seem to matter if spaces was on or off. However, I would recommend disabling it. Also the general stability of my machine also improved when I removed virus scanners and any non-essential software on boot up. I know these are general tips but I nearly gave up and bought a Windows PC but not everything works without any problem.
yes your are right. It's didn't work for me anymore... so I took the workaround:
1.) go to Preference Exposé & Space and disable the shortcut-option for direct changing to another space (normally made with something like CMD+1, CMD+2 ...)
2.) Download and install the App "HyperSpaces" (free version is enough)
3.) Go into the Preferences of HyperSpacpes, to "Shortcuts" and bind your desired shortcuts to every spaces.
I've done this some months ago and had no longer problems with a spaces hangup anymore.
I have had the problem with spaces freezing - not accepting keyboard input - with the icon on screen.
1) It DOES actually accept the change space keystroke (I use cmd + alt + arrow)
2) If I put my machine to sleep and wake it up again, the problem's gone (for at while)
3) If I change space by cmd-tabbing between my open applications, it won't freeze.
4) THe freezes just began for my within the last couple of weeks - and I've been using 10.6 for a really long time ,-) Might be some other softwre interfering I guess.
I have not yet envestigated, if it will freeze, if I change space using keyboard shortcut for going to a specifik space (using cmd alt number).
In a few times, it unfroze itself after lot of cmd alt arrow-changing.