All I remember from this movie is possibly a girl opening a guys casket (possibly boyfriend) and then I remember a scene where she is on a treadmill talking to him on a screen with his brain in a jar?! I thought the guys character was Ryan Phillipe but I can’t find this movie anywhere. I watched it late 90s early 2000s. It’s driving me crazy. Girl in the movie has blonde hair. I remember it being more of a chic flick or comedy.
This probably isn’t it, so sorry if not. But, considering the timeframe you mentioned, I wondered if the movie was “My Boyfriend’s Back”. That came out around the time you mentioned. But, I wasn’t sure if it matched what you talked about the girl talking to his brain in jar. If I remember any other movies I’ll post them, hope this helps.