[{HVY-E}Jinxx]

I've been dealing with things like this for quite a while as an IT professional.
Uncommon to popular belief and mass marketing, No one program will do everything!
Proper system protection requires a combination of different specialized programs working in concert to prevent and eliminate threats.

If it is a virus/spyware/maleware or hostageware, try the following:

1. Turn off system restore.

2. Reboot the system in Safe Mode with Network Support (Press F5 as the system posts)

3. Install Spybot Search and Destroy (Latest version).
- Run SBS&D and update it first. Then immunize the system and search for problems.
- After the firs run and cleaning, set SBS&D to run after next boot. DO NOT REBOOT YET.

4. Install and run Anti Malware Bytes
- Update first after install, then run a FULL scan.

5. Lastly, install Spyware Blaster
- Install and Update, then apply immunizations.

6. Re-boot the system normally and re-run the scans.

7. If everything checks out clean, D/L, install and run CCleaner.
- Run File scan first then run registry scanner.
- Reboot the system.

You're already using Avira, but if I were you, I'd either pay for the full version or switch to AVG free. This is due to the fact that AVG Free supplies Email scanning support, where as you only recieve that kind of functionality with Avira if you pay for it.