''Normally'' your ISP would not install remote control or back door software on your computer without your knowledge. To provide technical support, they might ask you to allow remote access or install a remote access program, and at that point their keyboard and mouse could do anything yours could do. I personally would be reluctant to allow that, because what I've heard from various people is that they will change things for their convenience without fully explaining what they did, and sometimes delete data without even asking if you have a backup. If you have the patience for following various troubleshooting procedures, you will retain more control. About resetting browsers: all major browsers now have a reset feature (Firefox's is called Refresh), but these are designed to preserve your most important data, such as bookmarks and saved passwords. Your ISP might be planning to use that feature, or they might be thinking of just deleting everything. This is why it is preferable to retain control. (And make backups!) If you think there might be some kind of remote access software or other spyware on your computer, you could try the tools and forums in our malware support article: [[Troubleshoot Firefox issues caused by malware]].