If you had not installed anything and it just started happening, I would think a corrupt data setting, and either clear caches and reset, or try restoring from a backup. As a last resort I would re-flash the ROM and start over.
For kernels, I have found that Garwynn's one from the SXTP site is the most stable. It doesn't support OC without using tegrak overclock. However it is more stable with certain apps over Agat's 1.3 kernel (example the gallery app and video player app FC if just opened without using a file explorer to select the picture or movie to play first).