You could run the uninstaller in a batch or vbs file with the -uninstall parameter before run the installation within other command line for installing it.

Parameter extracted from here: http://forums.adobe.com/thread/659747

I've been having a bit of a nightmare with this recently.  Both the Flash ActiveX and Flash Plugin's have been causing me a proper headache!

I support a mix of Windows XP and Windows 7 (32 and 64 bit) OS's and deploy Flash via GPO's.  I noticed some of the Flash updates were not being installed.  When I tried to manually remove them I was getting the message:

Error 2753.  The File 'InstallPlugin.exe' is not marked for installation. (Flash plugin)

or
Error 2753.  The File 'Installax.exe' is not marked for installation. (Flash ActiveX).

Anyway what I found was it was the previous version of either ActiveX/Plugin that caused the problem.  For example if 10.2.152.32 was showing as the version in add/remove programs,  I had to reinstall the previous version e.g. 10.102.1.64 before I could go forward.

I'd already tried all the above mentioned fixes, none of which helped. As soon as I installed the previous version it then allowed me to remove it.  I then rebooted the machine (having run gpupdate /force)  and the latest version was then installed via GPO.

The bad news is this is a manual process and I havent got a way to automate it so if you have thousands of machines its a tricky one.  That said I'm sure someone can come up with a script to find the version and reinstall the previous version.

I hope that makes sense and it helps someone out!

Tully, I feel your pain.

I have exact the same issue, I have deployed Flash via MSI over the years without issues.

I for some reason have got the Installax.exe error.

Not sure what the exact problem is but haven't been able to fix with, have tried creating custom MSI's with Orca, using scripts from here etc.

I have found that I can

1. re-install old version via GP

2. Then update to latest via GP

But I think you would need to find the first version of Flash MSI which you installed on the clients.

I have deployed 4 versions, one which is 10.0, another 10.1 and two from 10.2.

Along the way one of these versions has somehow messed up, am not sure what but it has.

The major issue is, that when deploying the latest version, it uninstalls the previous version, errors with the "InstallAX.exe" and then leaves the clients without flash installed.

I have registered the bug with Adobe on their bug system, on the 26/04/2011, but so far have had no reply, but the bug has been marked for "Internal Review", hopefully when 10.3 is released as an MSI we can roll out succesfully.

Had to reregister for some reason couldn;t remember my login lol.

MrTTM your a genius, I found the faulty registry entries and cleared them, and the new one deploys fine.

So I created a regfile that cleared the program files entries

Then deployed the latest MSI.

I have only deployed to two rooms, not done everywhere, as want to test and make sure everything is OK, before a mass roleout.

Many thanks.

"Installing v10.1.82.76 via MSI and then installing v10.1.85.3 via  MSI worked.  I have no idea which if any of the previous steps helped  the latter succeed."

Ahha! you have now given me an idea which has now fixed my gpo installer issue which has been a problem for months.

The issue was the same as the original poster, you get a file not found error while trying to install flash from MSI or by group policy.

SO taking mr in_the_uk's advice, i went back over all the old flash installs ( we keep them all in versioned folders, so that the GPO can upgrade any older version which may exsist). SO i went back through all the old installs and kept clicking on them, further and futher back in time, till i found an MSI which DID install without complaining!

I was then able to install overtop the newest MSI and it worked fine. It seems that for whatever reason, like 6 or 7 versions ago, i had not uninstalled the flash player cleanly. This method simply reinstalls the problematic previous flash player, which then enables you to perform an upgrade or install without the newer player complaining about files not marked for install.

I think this is the key. Previously on XP machines, i simply used "windows installer clean up" utility to accomplish the same thing, but this no longer works in win7.

As long as you have the old flash MSI file, you can easily repair the old install (even if it has been uninstalled already) and get back on track.

Thanks mr UK for the helpfull hint!

There are a lot of postings to this question so I would like to suggest a commercial solution to it. PolicyPak is a group policy based desktop management system that delivers and locks down third party application settings for applications such as Adobe Flash.  It's also available in two free modes, trial mode and community mode so it costs you nothing to check it out.  Its management interface simply snaps right into Group Policy Administrator which you already know.  It even provides a GUI interface for you to confgure your desired settings that emulates the interface of the application.  Go here for more information http://www.policypak.com/products/manage-flash-player-using-group-poli cy.html

One more thing, besides giving you the ability to completely manage Adobe Flash, it also supports more than fifty other applications to boot.