Help Cannot Mount to PC

[Poke598]

I have an LG Optimus One P500h that is just over a month old. I noticed in the last couple of weeks that whenever I connect it to my PC via USB, it only charges. It worked fine until one day. I have tried enabling USB Debugging and Mass Storage modes in the settings, and combinations of other settings. I tried different USB ports on the computer. I also tried reinstalling the USB drivers on the computer. When all else failed, I did a factory reset of the phone and formatted the Micro SD card. Nothing seems to work.

The only thing I can think of that I did differently was plug the phone into a rental car which had a USB port. I was trying to charge it and it kept going into mass storage mode. I don't think the phone has displayed the USB Connected dialogue with my PC since around that time.

Any ideas?

 

[Poke598]

Also, I've noticed since installing this card that many of my pictures and videos will be unreadable after they are taken. Sometimes the thumbnails go black days later and when I try to open videos I get the error "Warning! Cannot play this contents".

For example, my pictures often look like this after they are sitting in the gallery for even a few minutes:

Sometimes the colours are messed up too. Often purples and greens on certain parts of the pictures.

Mp3s sometimes say they are unsupported or are garbled when they're played.

It seems my phone is having trouble writing to the card. Should I replace the card?