Of the three R15 models (-100, -300 and -500), only the -500 has had a recent software upgrade. The current version for it is 10E8.
Another update is expected, however recent events suggest that it may be a little longer in coming than previously anticipated. A very limited test release of 10F1 appears to have resulted in a number of problems being identified, and there has been no indication as to how long it may be before those are resolved.
If you are having problems and a regular reset does not resolve them, you should then try the "reformat" or "clear and delete" reset. From the menu, it is "reset everything". That generally tends to clear out the cobwebs and get the R15 running smoothly again, however it also erases anything you have already recorded.
Carl