Hi, I am having the same problem today, it's been three hours now.
.I have reinstalled the sl viewer and also restarted my router. I have tried to do the 'test avatar' step mentioned above but nothing happens on screen.
My inventory (recent) says 'fetching items since logoff' and my clothing folder says ' Now wearing no outfit'.
I have been into preferences and moved the sliders to the left as many help forums mentioned this.
I am not very techy but i know i use windows 7.
Last night i was at a fairly busy sim and had no problems at all.
be glad of any help, thank you.