We have identified issues that can result in tabix giving a segmentation fault.

1) Tabix does not support the UCSC header line. You'll have to remove this line
track name=blabalh description="more blah blah"

2) Columns in a bed/gff file must be seperated with tab characters, not with regular spaces. Tabix will give a segmentation fault when trying to index a file with spaces instead of tabs.

3) There should be no comment lines (lines starting with #) in the bed/gff file.

4) There should be no empty lines, or lines with only white spaces.

Indexing of features files should only be done with very big files. Small files (up to a several megabytes) can be loaded without indexing and will result in superior performance.