Why am I unable to have friends of the opposite sex without these happening at least once?

Yesterday I sent an email to a friend who I've not spoken to for a few weeks, only to get a reply back asking why I never tried to speak to her anymore. When I tried to continue the conversation, she emailed back saying she got the impression I wanted nothing to do with her and asking me to let her know what was wrong and whethwe we could sort it out.

It was all in all a most bizarre exchange and did lead me to wonder whether it is possible to have a close male/female friendship without at least one emotional flashpoint. Any thoughts on whether thsi is the case?