chmod -t /home/corvette/ 644=uh oh!

[Corvette]

Oh great, when I chmodded my home directory on my one user Ubuntu 5.10 RC1 system to 777, GDM complained at me but would let me on. I thought the thing said it had to be 644 so I chmodded my directory to 644, but then the whole system went haywire, apps wouldn't launch, and even worse KDE would refuse to start! So basically, I have a whacked Linux system. Is there any way I can fix it...?

[SensoVision]

actually there are not much files which should have permission 777, it's always better for security to keep lowest permissions as possible since by making them 777 or so you're making all files executable which isn't good idea...
you're right that most files in home directory have permission 644 but most directories have to be 700 or 755 in order to make files in them readable. if you make directories with permission 644 you'll get into the troubles...
If you can't login into your account I would suggest to try

Code:

chmod -R 755 /home/corvette

and see if it would let you temporarily use your home directory for login, if you fail with 755 try 777 again.
And right after this I would try to make new user and copy from your old home directory all essential files e.g. form programs which are hard to configure and of course you documents and so on(I'm suggesting such solution and I guess that there is no magical way which would let you restore all permissions to default and leaving them in other state could lead to unexpected bugs in programs).

BTW I wonder what was the reason to chmod home directory? I admit that I did something like this too when just started my experience with Linux but I didn't brake the system since I had my home directory backed up

PS if you decide to create new user, try not to use old config files but rather configure them manually in order to avoid copying file with wrong permissions.
PSPS there actually another way to restore permissions but it's not time wise at all: you can create new user and while you're logged under it, fire up programs which you're using so they create necessary config files, after this you can use them as reference for correct permissions...

hopefully something from this would help, let me know if you need more help or anything from above wouldn't work, maybe I'll have another idea...