More information is needed.
Does this only happen with one file or if you create a brand new file, does it show the same behavior?
If a new file does not show this behavior, your file is likely damaged. You can attempt to repair it with the recover command or, best practice: replace it with an undamaged back up copy if you have one.
I am having problems with my car, what should I do?
Ummm, there are problems and then there are problems.
Thanks for your advice
When using a new small file as you kindly suggested the same problem exists. I have also tried making a clone and reimporting the records but no improvement there.
That result suggests your file is OK, but your computer and/or installation of FileMaker has an issue.
Use some utilities appropriate to your computer's Operating System to check/repair the hard drive and user accounts.
Try re-installing FileMaker.
On my Windows XP system, both FMP 10 and 11 are quite stable.