Seems like i have run into the unsolvable issue of sh404 not playing nicely with K2 attachments
This is on Joomla 1.5.24 / Latest sh404 and K2 2.4.1

[Dont tell me to upgrade - I cant yet as waiting for other components to be upgraded before I can use K2 2.5 :)

Posted about it here:
anything-digital.com/forum/extension/sh404sef/1988-issue-with-malformed-urls-using-sh404sef-and-k2.html#p12646

Checked the bug tracker here:
code.google.com/p/joomlaworks/issues/list?can=1&q=sh404&colspec=ID+Type+Status+Priority+Owner+Summary+Opened&cells=tiles

Does anyone have a solution for this?

Desparate to hear