Try to remove your memory card and see what happens.. somehow, your phone and memory card is sharing some resources which may affect phone memory integrities. you may want to check your memory card also for some viruses. your phone is can't or can be affected by viruses but all i know, java phones can't be. still, run a virus scan on your memory card, back it up and format your memory card from your phone.
i would not suggest to hardreset your phone cause i don't think you should do it. for its a sharing resources problem.
send me again a comment if it doesn't resolve your problem.
Answers & Comments
Try to remove your memory card and see what happens..
somehow, your phone and memory card is sharing some resources which may affect phone memory integrities.
you may want to check your memory card also for some viruses. your phone is can't or can be affected by viruses but all i know, java phones can't be. still, run a virus scan on your memory card, back it up and format your memory card from your phone.
i would not suggest to hardreset your phone cause i don't think you should do it. for its a sharing resources problem.
send me again a comment if it doesn't resolve your problem.
good luck and take care.