My keyboard commands in Adobe Illustrator aren't working after the new update

Question

Hello,
I like many others have done the new software update for the Mac - OS X Yosemite. And theres been a few bugs I've experienced. Along with slow internet my Adobe Creative programs have been acting up.
Mainly Adobe Illustrator CS5.5 - first was the font preview playing up but have fixed that with reduce transparency option. But now and the more annoying one is keyboard command keys are not working.
Main ones I have notice so far are: Delete, Shift + Command anything, Tool Bar shortcuts i.e Selection Tool (V) etc.
Its incredibly annoying and is actually interfering with my ability to work especially the simple one of deleting. I have seen a lot questions similar but to other programs and other suite versions. Please have anyone found an solution or please Adobe gives us the key to resolve this as it is a major inconvenience and is stopping productivity.
Many Thanks
Phoebe K

Answer 1

Phoebe,
Item 7) in 5) (follow the link) in the general list below shows the usual suspects. You may use that to find out which to avoid.
The following is a general list of things you may try when the issue is not in a specific file (you may have tried/done some of them already); 1) and 2) are the easy ones for temporary strangenesses, and 3) and 4) are specifically aimed at possibly corrupt preferences); 5) is a list in itself, and 6) is the last resort.
If possible/applicable, you should save curent artwork first, of course.
1) Close down Illy and open again;
2) Restart the computer (you may do that up to 3 times);
3) Close down Illy and press Ctrl+Alt+Shift/Cmd+Option+Shift during startup (easy but irreversible);
4) Move the folder (follow the link with that name) with Illy closed (more tedious but also more thorough and reversible);
5) Look through and try out the relevant among the Other options (follow the link with that name, Item 7) is a list of usual suspects among other applications that may disturb and confuse Illy, Item 15) applies to CC, CS6, and maybe CS5);
Even more seriously, you may:
6) Uninstall, run the Cleaner Tool (if you have CS3/CS4/CS5/CS6/CC), and reinstall.
http://www.adobe.com/support/contact/cscleanertool.html