Exclamation [Q] Stuck sometimes while unlocking sim, and strange "error" in status bar

Hello. Sometimes when I turn on the phone and unlock the SIM with my PIN, it just gets stuck in the unlocking SIM message. The phone gets signal, even internet access, and I get notifications, everything runs OK behind, but I can't use the phone because that message is there in the middle of the screen. Not even enabling airplane mode fixes it, I have to reboot. I haven't tried removing the SIM, though. I recently wiped everything > flashed a factory image > flashed cataclysm > flashed franco BUT it already happened before and keeps happening now.
Also, sometimes I see a strange error in the status bar (more often when the SIM problem occurs? dunno). In Spanish (the language the phone is set to) it says:
"El acceso restringido se ha modificado"
Which in English is, more or less:
"The restricted access has been modified"

When I pull down the notifications, it's already gone, and the phone keeps working perfectly

I can't RMA it (it's not officially sold in the canary islands, well, it is via amazon but when they announced that it was too late), so I hope it's a bug. Any ideas?

I think it would be useful to know that it's a real microsim (not a cut-down SIM), a movistar one, and I don't have any other microsims to test or other phones that use microsim. The phone is from the UK.