I have installed joomsef and i am pleased with the results, but i have a problem.
When a user tries to log in they are diverted to this url: \"iow365.com/index.php/component/option,co...5.com%2F/\" which is a blank page.

I can resolve this problem by unchecking the \"Search Engine Friendly URLs\" in the \"SOE\" Global Configuration back end, but of course by doing this joomsef no longer works.

My version of joomla is 1.0.3.

if anyone could help would be great...thanks.....Jona....http://www.surf-webdesign.com

Are you using the standard com_login module (component) for user log-in?
This seems like a problem of some customized code.

Turning \"Search Engine Friendly URLs\" turns off all SEO, including JoomSEF.
Does the log-in work when JoomSEF is off (in JoomSEF config), but Joomla! default SEO is on?

The URL you have posted is not JoomSEF generated URL, but the Joomla! SEO URL. If the logging does not work with default Joomla! built-in SEO, it will neither work with JoomSEF.