Hi Quite a while ago I installed the above and trialed it. Now when I try to uninstall all I get is the following message. "c:\ Program Files\ Advanced Registry Optimizer\unins000.dat"
Could anyone offer some advice please.

I'm not sure if this program is related to a recent adware/malware program I was able to help someone get uninstalled, but it sounds like it may be. Trying this can't hurt and will only take a few minutes:

Please download Malwarebytes' Anti-Malware (MBAM) to your desktop:
Malwarebytes' Anti-Malware - Free software downloads and reviews - CNET Download.com (http://www.download.com/Malwarebytes-Anti-Malware/3000-8022_4-10804572.html)
Double-click mbam-setup.exe and follow the prompts to install the program
At the end, be sure a checkmark is placed next to
Update Malwarebytes' Anti-Malware
Launch Malwarebytes' Anti-Malware
Click Finish.
If an update is found, it will download and install the latest version.
Once the program has loaded, select Perform full scan, then click Scan.
When the scan is complete, click OK, then Show Results to view the results.
Be sure that everything is checked, and click Remove Selected.
When completed, a log will open in Notepad.
Are there entries in there reporting the removal of Advanced Registry Optimizer? There should be...

NOTE: MBAM is a free to try piece of software, but it is fully functional when downloaded. If you find it suits your needs, consider purchasing a license since that would give you a version that can be "on" all the time and providing real-time protection against programs that appear to be harmless/helpful tools and aren't. MBAM will spot these and stop you from installing them if you have the licensed version.