Are you talking about Spyware Doctor? If so there is a version that is free from pack.google.com that is the same as the full version except for some of the active protection features are disabled. Also you can get Spyware Doctor for $20 per year.
When you want to buy protection, search for the product name and "coupon code" in the same search and you'll find good deals. For instance: "SpySweeper coupon code", or "Spyware Doctor coupon code". Both of these are excellent.
As for your problem if you are using PC Doctor, I couldn't find anything current about it. Is it the software that came with your computer form the vendor, Compaq, hp, or Gateway? If that's the one, I wouldn't bother using it.
For free protection I would suggest, AVG Free, BitDefender, AntiVir, or Avast. Anti-Spyware, Spyware Doctor from the Google Pack, AdAware, Spybot Search and Destroy, and for online scans do the Trend Micro House Calls. The Norton Scanner offered with the Google Pack is more of a headache than is worth having.
http://www.viclovan.com/how_to.htm
All that being said, it was a false positive just like q said. There's nothing malicious about CCleaner. While I've had an issue with CCleaner in the past it was minor glitches(and hopefully being looked into), and cleaning ease of use that it provides is second to none. About the false positive, I'm a tech and I use, and have used, many security programs in the past and have not had even one of them id CCleaner.
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EDIT!!!
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I have to eat SOME of my words! In order to do that though, I had to use old versions of both programs. I now think you must have been using Spyware Doctor for sure. I had to work on a machine today with version 1.41 of CCleaner and as soon as I tried to open it, Spyware Doctor popped up a warning that it had blocked CCleaner. Before I updated Spyware Doctor, I updated CCleaner and that solved the problem and opened up just fine. I then updated Spyware Doctor as well. I would be willing to bet that CCleaner was old on your system and that's what caused the false positive.
Also if your Spyware Doctor isn't registered because you already have the free version from Google you are fine but I might update it.
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Below is what was listed in the log for Spyware Doctor.
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1/14/2008 5:58:41 PM:748
OnGuard: System Event Blocked
Threat Name - Trojan.Tagasaurus
Details - Spyware Doctor has blocked an application attempting to access a file.
Risk Level - High
Infection - C:\PROGRAM FILES\CCleaner\CCLISTVIEW.OCX
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