Bitcoin QT error

When I open my Bitcoin QT wallet, I get an error saying "Error opening block database. Do you want to rebuild the block database now?"

I aborted and re-opened the wallet and got the same error. I then tried rebuilding it, and after a looooooong time (at least 24 hours), it started working again last night. When I booted up my computer this morning and opened it up, I’m getting the same message again.

Any ideas?

edit: Wow, I really appreciate the quick response, everyone! I’m glad this community is so supportive.

Since I made my post, I repaired permissions on everything and did a reboot and it’s currently working. I’ll keep this bookmarked in case it fails again.

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