REGISTRY_ERROR; blue screen of death

Please bear with me as I am not the most computer savvy of people. But I hope someone can offer advice as to my problem:

I own an Inspiron laptop, have had it since July and it's been working fine up until now. Upon switching it on, immediately after the Dell logo appears a message is displayed: "Windows failed to start. A recent hardware or software change might be the cause." I have not made any hardware or software changes. I am given the option to launch startup repair or to start windows normally; whichever one I choose results in startup repair being launched. Halfway through it cuts to a blue screen with the message REGISTRY_ERROR and at the bottom the technical information: "*** STOP: 0x00000051 (0x00000003, 0x00000001, 0x001F3000, 0x8D9A7F30)".

Since the Dell customer support lines are busy this is my only avenue of advise. Could someone please explain to me what the problem is, and how to fix it?