Can't submit forms when using URL rewrite

[eluser]dallen33[/eluser]
I figured it out, although I'm not sure why this was causing the problem. I had the following redirect that added a slash to a URL if it didn't contain one.

Code:

<rule name="Add trailing slash" stopProcessing="true">
    <match url="(.*[^/])$" />
    <conditions>
        <add input="{REQUEST_FILENAME}" matchType="IsFile" negate="true" />
        <add input="{REQUEST_FILENAME}" matchType="IsDirectory" negate="true" />
    </conditions>
    <action type="Redirect" redirectType="Permanent" url="{R:1}/" />
</rule>