Operating System not found - F2 - F10

It sounds as if the CMOS battery is dying.

Next this occurs, enter the CMOS, navigate to your drive configuration, select the hard drive, and press Enter to reset the current configuration. Then Save and Exit the CMOS. See if that helps.

Try the "Questions" forum; the "Discussion" forum is for matters of general discussion, not specific problems in search of a solution.

Post problems such as this to the "Question" forum, rather than the "Discussion" forum. There are those who specifically seek out problems in need of a solution, and that's where they go to look for such.

Additionally there are the benefits that:

1) The "Questions" forum provides for your feedback, by way of your being able to mark "helpful" responses as such. This does not necessarily mean that a given response contained the complete solution to your problem, but only that it served to guide you toward it. This is intended to serve as an aid to those who may in the future have a problem similar to yours, so that they might have a ready source of reference available, thereby perhaps obviating the need for them to repeat questions previously asked and answered.

2) The revised TR makes it quite difficult to find both "Discussions" and "Questions" that have not had a fairly recent post, owing to some functions comingling them in the listings. By keeping each type in their respective forums, it is easier for all to find what they are looking for.