Signatures Not Visible When I Sign In to Forum

I've noticed that signatures at the bottom of posts disappear if I sign into the forum.

 

For example, the signature for Robby's post here showing his system specs [NIS 2013, GHOST 15, NU 15. Win XP SP3. 2004 Toshiba 17" laptop, 3.1GHz "dual-core" cpu, 1.5 GB mem (max 2.0), 80GB HDD] is only visible when I'm signed out.

 

Has anyone else experienced this behaviour?

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MS Windows Vista Home Premium 32-bit SP2 * Firefox 24.0 * IE 9.0 * NIS 2013 v. 20.4.0.40
HP Pavilion dv6835ca, Intel Core2Duo CPU T5550 @ 1.83 GHz, 3.0 GB RAM, NVIDIA GeForce 8400M GS