viewports unwantingly switching to perspective

[powerandrubber]

For some reason since switch from 2008 to 2009, my ortho viewports are constantly switching to perspective when editing. Particularly when using the top view which I always want to be orthographic. I can't purposely make this happen but when editing in an orthographic viewport it annoyingly switches to perspective for no apparent reason. I have viewcube turned off because I'd always accidentally click on it when editing. (would be kind of a nice feature if it was display only) Any ideas? Please?

[MegaPixel]

If I recall, there was a patch released shortly after which was supposed to correct this along with a host of other big bugs. Are you running the service pack or any updates?

[powerandrubber]

Thanks man! Installed SP1 and so far so good. Must have forgot to install it when I upgraded to win7 last fall