Excel 2007 - "Cannot complete this task with available resources"

The problem can be found in the title. I've been using Office since a very long time. Office 2000, 2003, and now 2007. My office is the Hungarian edition, the SP2 patch have been applied through the Windows Update. So far, I've never seen this problem.

Basically when I try ctrl+a in a file, ctrl+c, and open a new file (ctrl+n), it pop ups this message.

As I said it's been working for a veeeery long time like this. The computer got 3gb free memory, enough CPU, enough everything. Tried applying the SP2 fix again, it didn't work. Found a hotfix for this, kb956506 but it didn't apply. It said "the expected software cannot be found on your PC".

Now.. I'm stuck. Any idea / suggestion are welcome..

NEW Information: It is an Office 2007 Basic OEM. I thought its an in-built limit but it was working for so long .... that just can't be the case. First it works and after someone it doesn't.

Oh yeah I forgot:
- Tried to remove AppData stuff, nothing happened.
- Tried to search for duplicates, but couldn't find anything.
- Total clean install, removing regkeys, settings, blah blah, didn't help.
- I don't have a .xlb file on my PC so deleting it ...is quite impossible.

Here is a video about the problem (Sorry, it is a Hungarian Excel.)
http://www.youtube.com/watch?v=mYO0Kh4VBrM

It turns out, Ditto is the problem here. Reported the bug, hope the Ditto devs will fix it since I really love Ditto and it's a must. Once you get used to it, you don't want to abandon it. (Like "Everything";"F.lux" and so on).

Apparently there is more than one reason for this problem.
Here are some references:

excel cannot complete this task with available resources
Two possible actions:

• Delete all files in C:\Documents and Settings\*USERNAME*\Application Data\Microsoft\Excel and reboot
• Search and delete file Excel11.xlb

Excel 2007: Excel cannot complete this task with available resources
Save as an .xslx file to solve the problem

Error message when you open a workbook that contains cells that you filled with a reference to a relative name in Excel 2007: "Excel cannot complete this task with available resources"
Although this doesn't sound suitable according to your description of the problem.

EDIT

See this article:
What to do if you get an out of memory or not enough resources message
which contains a lot of advice concerning this problem, too many to list here.

From my side, I would like to ask two questions:

1. What is the memory usage of Excel as seen in Task Manager?
2. What happens if you launch Excel from another user account (create one if required)?

EDIT2

Since it works under another user account, I would suggest to:

1. Uninstall Office
2. Verify that everything was really cleaned out as described here:
   How to manually uninstall the 2007 Office system
3. Run very carefully a few register cleaners, such as CCleaner, Eusing Free Registry Cleaner or TweakNow RegCleaner.
4. Reinstall Office.

If this doesn't work, then your user account is really unusable.
Then the best I can think of is to rename it, create a new account that has the same name, and use that instead.