Yes to what theducks said. Also blow out vents with air and put laptop on cake rack or something if it is running hot. Doesn't really sound like heat related but your drive may not be seated properly.
Another suggestion is getting an external hard drive and having your calibre library and anything important datawise stored on that. Not a big degradation in performance overall for me at least and internal laptop heat will not affect it.
That said I bought a lovely I5 Lenovo laptop for $329 (for my sister) including tax and shipping so selling your current laptop and upgrading could be the way to go. It runs very very cool even converting 1000 books.
Anyway as long as you have backups of all your important stuff on another drive, no real worries
Helen