I’m trying to install ModX 0.9.6 on an Ubuntu (Gutsy

) box running Apache2, MySQL, and PHP5. I can get through the first parts of the pre-install process fine, but when I get to specifying the database login info, the "Test Connection" button takes me to an incomplete page that has the ModX header but ends right after the following HTML, without showing any kind of error message:
<td class="pad" id="content" colspan="2">
<table border="0" width="100%">
<tr>
<td valign="top" nowrap="nowrap"> </td>
<td style="padding-left:20px;padding-right:20px;">
Similarly, if I ignore this and proceed with the installation, the Pre-Install Validation page gets to "Creating connection to the database:" and then hangs. Again, it doesn’t display any kind of error, just stops as if it were completely finished processing.
Does anyone know why an error like this might occur? Thanks!