Problem logging into online forum via mobile device

Hello there.

I have a problem attempting to log-in to a online forum from a mobile device (everything works OK using a PC).

The website is Irish LEGO User Group - Index

The problem occurs when I click on the Person icon at the top of the screen (right hand side). It opens a drop down menu with 'Guest' as default. When I select 'Login' from this menu nothing happens. To me it appears that the URL is not pointing anywhere and so selecting 'Login' sees nothing load.

Here is a link to a screenshot showing the Person icon circled in red.



Login does work from a mobile device from the Menu dropdown (see icon circled in green).


When I press on the not working login link the following URL displays: When I press on the working login link the following URL displays:
Relevant code:

I believe the code in question is on this file (I have copied it to an RTF file) http://www.lug.ie/forum/code.rtf and the relevant are concerns Wireless login attempts.

I did not write the code for the forum and although have fixed a number of other bugs this one stumps me. I would really appreciate any help with this as frankly I am lost in code.