This issue is very specific to 64-bit IE 8, 64-bit jre (both in regular and compatibility view). The same applet works fine in 32-bit IE 8/ 32-bit jre of the same version.

Tested OS: x64-XP-pro(sp3), x64 Vista Enterprise(sp1)
       Brwoser: 64-bit IE 8
       jre: 64-bit jre 6u13-b03, 6u14-b04

Steps to reproduce:
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1) On 64-bit Windows XP or Vista, using 64-bit IE 8 to browse
http://www.realarcade.com/community/games
2) Locate 'Addiction Solitaire' game and click 'Play Now'
3) Click 'Play as Guest' or signed in to play (should you have an account)

If the applet can't load, the problem is reproducible.