I have been using Flexbuilder 4 for several months now (on Windows Vista) and I regularly get this error and end up uninstalling, running the cleaup utility and reinstalling. But this is becoming intolerable as I am wasting hours of development time. Surely there must be a permanent professional solution, a patch, fix, new version? Please could someone advise me for a permanent solution, other than changing our development tool.
The Same problem pestered me for so long first of all you should remove your flash based adobe products and clean your registry using any free registry cleaners like cc cleaner or registry mechanic or tuneup utilities, such that all the traces are removed from the system.
After that reboot your system and then open the folder where flash builder is located and right click it and select run as administrator and install it. This Process should work fine and it went perfect for me.