P9 won't start due to supposedly older version being present

System: Apple Macbook Pro running Mavericks 10.9.3 (and since last week 10.9.4)
Software: ParallelsDesktop-9.0.24229.991745

Yes, I have seen that there have been posts about this, and yes, I have tried each and every single "solution" that was presented in such posts as well as those suggested by ParallelsSupport via twitter...

After a failed Parallels update due to network outage, I have been unable to reinstall Parallels and get it to start up properly by double clicking "Parallels Desktop.app" in Finder. It keeps on complaining about an older version being detected. When I press the "Remove" button in the dialog that pops up, I get the infamous error 15380 which has absolutely nothing to do with it. My system's configuration looks okay to me (no groups with same id and stuff like that)...

As root I have already removed every single file that is related to parallels, but to no avail. Using Instruments I have monitored the filesystem to try and find out exactly how Parallels determines that there is an old version present, but I can't seem to find it. Using a recursive grep in combination with find I have tried locating any files related to Parallels after cleaning my system, but nothing... Also tried modifying some of the scripts inside the "Parallels Desktop.app" package, but the debug info I added never pops up in the log...

When I start prl_client_app manually, Parallels starts fine...

I have found:
1) Support to be as good as non-existent and totally worthless, making me feel ripped off since I did pay for working software
2) It is unbelievable that no-one from Parallels can seem to indicate how Parallels Desktop checks for the presence of an older version.
3) I am beginning to believe that even though mac os x is supposedly completely file based, they also sport some kind of "registry" like database or xml somewhere which keeps track of all version installations
4) The only thing I haven't touched since I'm not sure on what is Parallels related, and what isn't, is the Qt stuff...
5) It is next to impossible to get proper support from Parallels...

I would appreciate a solution to this problem...I find it unacceptable that I have issues like this with paying software.

Excerpt from parallels.log:

07-07 12:52:53.664 F /PrlGui:89423:707/ Showing message box. Type = [Question, GUI_QUESTION_REMOVE_PREVIOUS_VERSION].
07-07 12:52:55.405 F /AbstractTask:89423:707/ Task InitializeAppBundle <0x1096881d0>: new subtask is InitializeBundle <5>
07-07 12:52:55.405 F /gui:89423:707/ (!)Error: can't get server instance to find out product edition
07-07 12:52:55.408 F /PrlGui:89423:707/ Deleting CMessageBox <0x115e56150>
07-07 12:52:55.411 F /PrlGui:89423:707/ Closing message box. Type = [Question, GUI_QUESTION_REMOVE_PREVIOUS_VERSION]. Answer = Remove [1] (0)
07-07 12:52:55.417 F /PrlGui:89423:cb23/ Connect to Authorization Services: The operation completed successfully.
07-07 12:52:58.552 F /PrlGui:89423:cb23/ Authorize: The operation completed successfully.
07-07 12:52:58.581 F /gui:89423:707/ Bundle initializaion has started, but failed with error 4
07-07 12:52:58.583 F /AbstractTask:89423:707/ Subtask 5 [InitializeBundle] completed with RC = 80015369 [GUI_ERR_APP_BUNDLE_INIT_FAILURE]
07-07 12:52:58.584 F /AbstractTask:89423:707/ Finishing task InitializeAppBundle <0x1096881d0> with RC = 80015369 [GUI_ERR_APP_BUNDLE_INIT_FAILURE]
07-07 12:52:58.584 F /AbstractTask:89423:707/ Subtask 6 [InitializeAppBundle] completed with RC = 80015369 [GUI_ERR_APP_BUNDLE_INIT_FAILURE]
07-07 12:52:58.584 F /AbstractTask:89423:707/ Finishing task StartApplication <0x110071aa0> with RC = 80015369 [GUI_ERR_APP_BUNDLE_INIT_FAILURE]
07-07 12:52:58.585 W [MESSAGE_MNG] /PrlGui:89423:707/
Message id: {3b6f21cd-2806-4a7b-962a-14bcf89766b1}
07-07 12:52:58.585 W /PrlGui:89423:707/
Message data:
>> Issuer id =
>> Code = GUI_ERR_APP_COULD_NOT_BE_STARTED
>> Type = Critical
>> Short Message = "Parallels Desktop could not be started."
>> Long Message = "Please try again. If the problem persists, contact the Parallels support team for assistance."
>> Details = ""
>> Spontanous = 0
>> Can be hidden = 0
>> Force show = 0
>> Use active = 0
>> Event handle = 0
>> Answers: [OK] [Send Problem Report] []
>> Default button number: 1
..>> Message hint: 0x0
07-07 12:52:58.585 F /PrlGui:89423:707/ Showing message box. Type = [Critical, GUI_ERR_APP_COULD_NOT_BE_STARTED].