MP2 is usually an audio file compressed with Mpeg 1-level 2. I think you really mean an MPEG2 video file, which can have a file name suffix of .MPG, .MPV, or .M2V ( and probably others I've never heard of ).
If you really mean an MP2 audio file, then think about how huge that is. At 384kbps, the typical bit rate for DVD type compressed audio, that means it's more than 14 hours long!
As far as your .wav file loading, you might want to let your PC set a bit after the load process indicates it's done. It may be busy transcoding the audio data into an internal working format or simply generating the quasi-waveform for display.
PS - Chucking a movie length MPEG2 into an editor like Premier always puts a strain on a PC's resources because temporary working files of even greater length are being made, since an MPEG2 compressed file can't be directly edited. It has to be decompressed first. If you don't have NTSF format hard drives to put them on, you'll probably crash every time the FAT32 file size limit of 4GB is hit.
Fav quote - "Experience is whatcha don't get 'till ya don't need it no more."
System - Athlon 1.4GHz, Win98, Hauppauge PVR250 receiver and compressor.
Software -Magix Movie Edit Pro 10, Nero 6 + NeroVision Express, Moho 4.61, PSP 8.1, Bryce, Quicktime 6.52 pro, Goldwave 5, DVD-Lab.
Cameras - Panasonic GS9, Canon ES8400V, Canon EOS D20 and Canon A70