installing soap ui not possible with licence key

Hi there,

Goal: install <ReadyAPI-x64-1.5.0_R883675825469> with a licence key from soap ui

Impediment: I get the following message: < The installation/removal of a previous program was not completed. You will need to restart to complete that installation. >  ... but after restarting I get this message again.

starting position:

1. machine A has soap ui free version & expired pro trial version 1.4.1

installation steps:

Day 1:

1.obtain licence key from soap ui. status: ok

2. insert licence key on machine A. status: ok

3. open soap and use application on machine A. status: ok

4. close machine A ( I have not restarted machine A on day 1)

Day 2:

1. on machine A open soap ui...result: java-error (see attachment <testresult 1: screenshot 1> )

2. on machine A remove soap ui free version & expired pro trial version 1.4.1. via control panel    status: ok (remark: they have also been removed from recycle bin as a result of running CCleaner below).

3. on machine A install soap ui version 1.5.1. ...result: I get the following message: < The installation/removal of a previous program was not completed. You will need to restart to complete that installation. > (see attachment <testresult 1: screenshot 2> )

4. on machine A restart machine and try again. result: same message.

5. work-around: install soap ui 1.5.1 on machine B. result: machine A has locked the licence key from soap ui.

6. work-around2: on machine A run CCleaner...result: no change,  testresult 2 (see above) still occurs.

7. Conclusion: I must (find a way to) uninstall the remains of soap ui on machine A

8. possible solution: remove soap ui from windows registry...I am not sure which entries in the registry must be removed.

My question:

Could you please tell me how to solve this issue (e.g. via the windows registry)? Any silver bullets out there? Feel free to shoot :).