For me it's a little different. After upgrading from LR3 to LR4,  LR4 doesn't crash but it does hang. After which, if I try to change the module, I get the error:

"An error occurred when attempting to change modules."

Mac OS X 10.7.3

iMac, Intel Core 2 Duo, 2.4 GHz, memory: 2GB

I purchased LR 4 today.  Though decided to download and start using as a trial.  Both 32 and 64 bit crashed from the start.

I looked over my catalog that I wanted to upgrade.  I saw some issues with RAW and edited from a Sigma SD14 that I previously owned.  I eliminated every one of those troubling formats from my LR 3 catalog/  Performed a save/backup.  I deleted the LR4 catalogs first created.  The restarted LR4 with my LR3 catalog.  Upgraded and now no crashing.

Maybe this gives some ideas to your own situation.

I shall keep LR 3 still installed for awhile until I am free and clear.

I will keep a back up of my presets folder just in case.

I have a similar problem.  Mine doesn't crash, but here is the message I get when I click on the Book module:  (unknown c++ exception).  That's all the information it gives me. I'm running Windows 7 on a Dell Studio 540, 8gb RAM, Service Pack 1.  So far, everything else with LR4 works great. I get no errors with any other module or panel.  I've been kinda waiting to see if anyone else was having a problem with the Book module ONLY.  There surely must be a common thread somewhere here.  And for the record, I did uninstall and re-install LR4.  That didn't help.  Sure would appreciate someone's help because I no nothing about c++ errors. Thanks.  Jack

I have the same problem with the Book module Jack.  I swear it was working before.  I did install Photoshop CS6 Beta today.

Bill

I have a similar problem but with a different module.  Running Windows 7 (64 bit), when I try to go to the Print module, the program hangs up.  Eventually -- like in half an hour or so -- it will unlock, I can switch back to Library or Develop, and continue to work.  But I can't print.

Yes I did try that.  Still the same thing.  But I'm going to try that once again since that's all I know to do.  If by chance the result is positive I will post it. Thanks.

Jack

I have the same problem. Click on "Book" causes "unknown C++ exception".

I already re-installed the program, deleted the preference file, tried it with a brand new catalog without pictures but nothing helped.

System: Win 7 64Bit, i5-750, 16GB DDR3, CS5 Master Suite german and LR4-Trial german (the error caused in the beta, too).

I also installed Lightroom 4.1 RC today and I still have the same "unknown C++ exception" when clicking on "book".  I think I will also mention some other programs that I have installed on this Dell Studio 540 with Windows 7 Professional. OnOne software's Perfect Suite 6, Photomatix, Portrait Professional, Daz Studio 4, Photoshop Elements 8, Debut Video Capture Tool, and a lot of "utility" programs that are too numerous to mention.  At some point when I have time I may try a uninstall/re-install of some of these and see if that does it.  That would obviously take an enormous amount of time.