That sounds like IGV is broken, likely trying to read a broken SAM tile. Convert to coordinate sorted BAM and reindex; then update IGV to whatever version they're on now; it should work.
I converted the file to BAM, sorted and indexed it all using samtools,again. Also, the IGV is in it's latest version v.2.0.30-1. I'm still getting the same error.
What kind of SAM file? Is it from a weird process or new technology?
I have SAM files from SOAP, RUM, BOWTIE2 and BWA.