From time to time, especially when I logout, I get a blank page, except for a drop-down list with nothing in it.

I'm using XOOPS 2.0.5 and wf-sections 1.0.1

When I look at the source of the blank page (with debug switched on) I find this:

<select name='id' onchange="location.href='http://127.0.0.1/xoops/html/modules/wfsection/index.php?category='+this.options[this.selectedIndex].value">
<option value='0'>-----------</option>
<br />
<b>Fatal error</b>: Undefined class name 'xoopsmodule' in <b>d:\apache\apache\htdocs\xoops\html\modules\wfsection\class\wfstree.php</b> on line <b>199</b><br />
Notice [PHP]: Undefined index: lang_rememberme in file d:\apache\apache\htdocs\xoops\html\templates_c\db%3Asystem_block_login.html line 7<br>
Notice [PHP]: Undefined index: sslloginlink in file d:\apache\apache\htdocs\xoops\html\templates_c\db%3Asystem_block_login.html line 10<br>
Notice [PHP]: Undefined index: xoops_lblocks in file d:\apache\apache\htdocs\xoops\html\class\smarty\Smarty.class.php line 626<br>
Notice [PHP]: Undefined index: xoops_rblocks in file d:\apache\apache\htdocs\xoops\html\class\smarty\Smarty.class.php line 626<br>


Any bright ideas? Am I doing something wrong?