Hi Leonard, so your /tmp permissions look ok.

I guess you could try upgrading from 10.6.x to 10.7 Lion, that could possibly reset whatever has gotten messed up. Either that or wipe the disk and do a reinstall of Snow Leopard.

That you have gotten different results since doing a volume repair certainly does suggest to me that something has gotten messed up on your machine somehow.

After you did that repair, you can now save files ok, is that correct? And it's just opening of specifically .ai and .pdf files that is not working for you? Do other file types like 3DM files open ok now?

- Michael