PC Repair Doctor is a system maintenance and repair tool. The application claims that it can effectively improve your system's performance by detecting and repairing all registry errors, reducing system crashes and errors, and protecting your privacy. To do this, the application offers three different optimization modes.
The first one is a smart system scan that looks for registry errors and privacy concerns in your system. A simple scan on my test system returned 5900 potential errors, varying in importance, or risk. Most of these errors had to do with privacy items, which I am assuming have to do with Internet privacy, so it must be talking about cookies and files like that. The rest of the errors had to do with missing help files and fonts, corrupted DLLs, etc. There is a button that reads "Fix All Errors Now" but it takes you to a website where you can buy the full version of this application. In other words, the trial version does nothing but scan your computer for potential problems.
The second feature is concerned with optimizing your system, but it is simply a start-up application manager. By unchecking a name on the list of applications, you will be removing it from your start-up list, so it won't automatically load when you start your computer. PC Repair Doctor will tell you how many seconds you have shoved off your start-up time and display an ad telling you that you can further optimize your PC if you buy other software.
The third feature is called "Backup and Restore". This one is pretty self-explanatory. PC Repair Doctor automatically creates restore points before each scan, but you can do this manually. These restore points are probably only your registry and configuration files, since a complete backup takes less than 10 seconds. None of your data will be backed up with this feature.
All in all, PC Repair Doctor is simply a set of 3 tools that are readily available online and for free. There is no way to test if the application works for you before you buy it, since the trial only scans for potential problems, but won't solve them. So, in a nutshell, the trial version of PC Repair Doctor simply lets you create basic restore points and remove applications from your start-up list.