There's two possible reasons for this.
I've had the same problem before
1.Usually the main reason for this is because there's long values in the tables you're importing and you did the export where direct=y. Try exporting via conventional then running your import. this fixed the problem with me
2.If you're ftp'ing the dmp file from one server another, how are your files copied/transported from the one to the other system. Be sure that it was done in a binary way. Some file-transfer programs/protocols do the job default in ASCII instead of BINARY resulting in very strange errors like you have. [size=1.5] as per metatlink article[/size]
Oracle it's not just a database it's a lifestyle!
BTW....You need to get a girlfriend who's last name isn't .jpg