when i try to open sidewinder i get this..

file_read('tags\levels\test\sidewinder\sidewinder.bitmap') error 0x00000026 'Reached the end of the file. '
couldn't read #108 bytes from offset #64 in local tag 'tags\levels\test\sidewinder\sidewinder.bitmap'
couldn't read elements for bitmap block
failed to load bitmap tag 'levels\test\sidewinder\sidewinder'
couldn't open tag

I what it means coould some one help me fix it?
like send me a tag that works? :P thanks