what does these exceptions mean?

Possible Duplicate:
what does this mfc appliction “First-chance exception” exception mean?

First-chance exception at 0x00939044 in Media.exe: 0xC0000005: Access violation reading location 0x00000048.

Unhandled exception at 0x77b515de (ntdll.dll) in Media.exe: 0xC0000005: Access violation reading location 0x00000048