Cannot install AIR 2.5 on Windows XP

After searching and reading in this forum for about an HOUR or so I still have no solution.

I've tried installing Adobe AIR 2.5, AIR 1.5, tried restarting the computer etc.

Nothing works.

I get a message similar to those posted by most users in this forum.

It says that there is an error and that I should make sure that I install it as administrator.

I already have administrator rights, of course!

Here is the content of the error log file:

[2010-10-27:09:34:59] Runtime Installer begin with version 2.5.0.16600 on Windows XP x86

[2010-10-27:09:34:59] Commandline is:

[2010-10-27:09:34:59] No installed runtime detected

[2010-10-27:09:35:03] Starting runtime install. Installing runtime version 2.5.0.16600

[2010-10-27:09:35:03] Installing msi at c:\dokume~1\XXXXX\lokale~1\temp\air49.tmp\setup.msi with guid {XXXXX-XXXXX-XXXXX-XXXXX-XXXXX}

[2010-10-27:09:35:07] Error occurred during msi install operation; beginning rollback: [ErrorEvent type="error" bubbles=false cancelable=false eventPhase=2 text="1603" errorID=0]

[2010-10-27:09:35:07] Rolling back install of c:\dokume~1\XXXXX\lokale~1\temp\air49.tmp\setup.msi

[2010-10-27:09:35:07] Rollback complete

[2010-10-27:09:35:07] Exiting due to error: [ErrorEvent type="error" bubbles=false cancelable=false eventPhase=2 text="1603" errorID=0]

[2010-10-27:09:35:11] Runtime Installer end with exit code 7

Of course, I have the newest Windows updates etc.

I have also the newest Windows Installer.

So, what is the big secret?

Do I need to buy a new computer in order to install Adobe AIR?

(the computer I have is fairly new, despite XP installed on it)