I have recently been having trouble with the recent UI patch. About a day or two after it's release, both Missions and the Arcade are entirely unaccessable to me. I don't know about Lockdown though. I'll go to the load screen, and it will indefinitely stay at 0%. If someone uses voice chat, I can hear them through the load screen.
Currently running Spiral Knights through Steam with an elevator pass equipped.
Here's my DXDaig if it's necessary.
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System Information
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Time of this report: 4/6/2013, 11:14:35
Machine name: KRITZ
Operating System: Windows 8 Pro 32-bit (6.2, Build 9200) (9200.win8_gdr.130108-1504)
Language: English (Regional Setting: English)
System Manufacturer: System manufacturer
System Model: System Product Name
BIOS: Phoenix - AwardBIOS v6.00PG
Processor: Intel(R) Core(TM)2 Quad CPU Q6700 @ 2.66GHz (4 CPUs), ~2.7GHz
Memory: 4096MB RAM
Available OS Memory: 3326MB RAM
Page File: 1646MB used, 5008MB available
Windows Dir: C:\Windows
DirectX Version: DirectX 11
DX Setup Parameters: Not found
User DPI Setting: Using System DPI
System DPI Setting: 96 DPI (100 percent)
DWM DPI Scaling: Disabled
DxDiag Version: 6.02.9200.16384 32bit Unicode
I'm currently having the exact same problem; the "Advance now" screen took well over 20 seconds to come up and took even longer for the elevator animation to play, then became stuck at 0%, wasting 10 Mist.
The messed up part is my main can access missions just fine, and it was working just fine up until today.
Edit:
It seems to be fine now but that was really weird.