What are “registry entries”, and why does a computer gradually slow down?

How do i fix a serious issues i'm having with Mozilla Firefox, unauthorized registry entries and MSI services?

• my Firefox stopped working about three days ago. every time i try to open it or uninstall it, a window pops up that says 'your computer must be restarted to complete a previous of Firefox. Do you want to reboot now?..yes or no'. first few times i hit yes. my laptop restarts and back to the same issue. i talk to a Mozilla Tech. he said: While working on your computer I have seen unauthorized registry entries, which might have been written by some self active software. It has corrupted the MSI services and made some changes in your windows registry files. This are the services that are needed to download and install any application on your PC. To fix this issue I have to remove the trace of this software and fix the registry file configuration. so that I will be able to fix and restart the MSI Services on your computer. Also, we have to fix the corrupted others files, that might affect your PC later. and then he told me there would be a fee of $99.99 for one time fix. i thought that was ridiculously expensive for one time so i refused his assistance thinking someone can give me a push in the right direction here. So basically, i need help with: how to deal with unauthorized registry entries how to fix the corrupted MSI services how to remove the trace of the 'software' and fix the registry file configuration how to fix the other corrupted files It would be great if someone can help me asap. (don't want my laptop ruined) PLEASE AND THANK YOU

• Answer:

  Back Up all your important data and restart the computer > Hit F7 During the boot screen> Select Your Windows OS and Hit F8 for more advanced options> Select Safe mode (NO NETWORKING)> Log In and hit START> Type System Restore in the Search Programs and Files box (windows 7) > Click Choose a different restore point > Go back as far as you can. Select the stuff and keep going till you restart. For XP try To resolve this issue, follow these steps: Log on to your computer as an administrator. Click Start, and then click Run. In the Open box, type cmd, and then click OK. At the command prompt, typemsiexec.exe /unregister, and then press ENTER. Type msiexec /regserver, and then press ENTER. Verify that the SYSTEM account has full control access permissions to the HKEY_CLASSES_ROOT hive in the Windows registry. In some cases, you may also have to add Administrator accounts. To do so:Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base: 322756 How to back up and restore the registry in Windows Click Start, click Run, type regedit in the Open box, and then click OK. Click the following registry hive: HKEY_CLASSES_ROOT On the Edit menu, click Permissions. If SYSTEM is not listed in the Group or user names list, click Add, make sure that the local computer name appears in the From this location box, type system in the Enter the object names to select box, click Check Names, and then click OK. Click SYSTEM in the Group or user names list, and then select the Full Control check box under Allow in the Permissions for SYSTEM box. Click Apply, click OK, and then quit Registry Editor. If not get the OS disk that matches your comp, put it in the drive. Restart Hit F12, start the CD and run the OS Repair, Dont reformat until you know you've tried everything