Photoshop CS5 - Completely unusable.. help!

Question

OK.. where do I start...
My company recently purchased a licence for Photoshop CS5 (Mac) at my request, and I am now stuck in the unenviable position of telling them it was a complete waste of money.  Hopefully someone can help me resolve some of these issues and save my butt at the same time...
Problems:
1. Won't quit.  Whenever I launch PS, even if I do nothing.. I can't quit.  Selecting Quit from the menu does nothing, nor does Command+Q.  I have to force quit every time which means none of my preferences are saved.
2. Images don't update.  If I open ANY image with more than one layer, selecting/unselecting layers doesn't change the image.  For example, if I have an image with two layers in which only one is selected, then I select the second layer nothing will change on the image until I actually draw on it or make some sort of change to the image.  In other words, it's not re-rendering when I select different layers.  There are other situations in which this occurs but this is the easiest to explain/reproduce.
3. I can't create a New image. If I select File->New... I get the New Image dialog, but clicking OK does nothing except make the dialog dissappear.  So I can't create any new images.  This seems to happen intermittently though.. sometimes it works, sometimes it doesn't.
4. General performance.  I have a fairly new MacBook Pro (Intel Core i5 2.4 GHz, 4GB RAM) but photoshop is appallingly slow to use.  Just general use (opening images, selecting tools etc) takes several seconds to execute.  Way more than any other app I use.
5. If I run Photoshop in 64bit mode I am greeted with the following error at startup, "Could not complete your request because of a program error."  No idea what the error is, but I'm assuming this is a bad thing.
I have tried uninstalling/reinstalling.. no change
I have tried removing with AppZapper and re-installing.. no change
I have tried running in 32bit mode vs. 64bit mode... no change (other than the error listed above for 64bit mode).
I have noticed the following errors in the system log.. not sure if they are relevant:
/Applications/Adobe Photoshop CS5/Adobe Photoshop CS5.app/Contents/MacOS/Adobe Photoshop CS5[24480]: MDS Error: unable to create user DBs in /var/folders/B3/B3RE+qikH74rCK1Evpl+ik+++TI/-Caches-//mds
Adobe Photoshop CS5[24480]: -[NSCFString _getValue:forType:]: unrecognized selector sent to instance
At this point, Photoshop is completely unusable for me.  I'm sure it's more likely to be something with my setup (although it's pretty much a vanilla Mac setup), but either way I need some help!
My Mac version is:
10.6.7
Photoshop version is:
CS5 Extended 12.0
Any help appreciated.
Thanks!

Answer 1

Thanks for the reply.  I appreciate that millions of people are using Photoshop.  I simply hoped that one of those millions may have some useful tips to help be diagnose and (deally) resolve the problems.
I have updated Photoshop however the same problems persist.
I have also discovered that the issues with not being able to quit, and not being able to create a new image are limited to running in 32bit mode.  If I run in 64bit mode I am able to do both of these, however I still get the error at startup.
General performance is still very slow however. For example if I "long press" on the shapes tool (to display the context menu for shapes) selecting a shape from the context menu takes about 10 seconds to resolve.  During this time the CPU spikes to 100%.. all used by Photoshop and the entire machine is locked up while the CPU is maxed out.  Indeed this is observed for any context menu accessed from the Toolbox.
I haven't profiled it, but I'm assuming the slowness I see elsewhere is due to a similar effect.. namely CPU pegging.
I do not have any 3rd party plugins at all (it is a fresh photoshop install).
I have no idea what a haxie is, however after reading wikipedia (http://en.wikipedia.org/wiki/Haxie) I am fairly certain I do not have any of these installed.
I also understand that it is almost impossible to "fix" my issues from this brief explanation without knowing the full setup of my machine, however I am not necessarily looking for a solution, merely some guidance as to how to diagnose the problem so I can provide more meaningful data.  Are there any logs produced by photoshop that I could inspect to help me diagnose?
Thanks.