General :: ExtSD Card Causing Phone Instability?

I am trying to figure out if one it is possible for an SD card to cause my phone to become unstable (like spontenously rebooting, heating up, etc), i think the answer is yes as I have tried using the phone for a few days with and without the card and it does indeed seem more stable without the card but its less clear about if its the card or whats on the card. I tried formatting the card and thought at first that it was more stable but then it seemed to start acting up again (I can't sit and watch it all day and sometimes its not obvious that it has restarted, sometimes it just shuts down). I have also tried different versions of RR, tinkered with neartrom (not long enough to be sure though) but still stability issues.

Is there a way to see If my card is someway corrupted? or If the phone is just not liking this card or any cards? A friend let me use their card for awhile and my phone was still acting up (rebooting, freezing, overheating). I prefer to to figure out exactly what the problem is before I fork out the money for a new card; it seems illogical that a sdcard in general should make a phone act up like this but I am running out of ideas (going out and getting a new phone would be even more painful than getting a new sdcard so I am really hoping to figure this out as it seems to run ok when no card is inserted).

btw, I the card is a sandisk ultra 64gb microsdxc card, its worked for like 2 years (I stored music and backups on it mainly, most the r/w stuff was from daily podcasts).