Hi @txdv, would you provide your system information as requested here: https://github.com/ValveSoftware/steam-for-linux#reporting-issues

Processor Information:
    Vendor:  GenuineIntel
    Speed: 2669 Mhz
    2 logical processors
    2 physical processors
    HyperThreading:  Unsupported
    FCMOV:  Supported
    SSE2:  Supported
    SSE3:  Supported
    SSSE3:  Supported
    SSE4a:  Unsupported
    SSE41:  Supported
    SSE42:  Unsupported

Network Information:
    Network Speed:  

Operating System Version:
    Ubuntu 12.04.1 LTS (32 bit)
    Kernel Name:  Linux
    Kernel Version:  3.2.0-24-generic-pae
    X Server vendor:  The X.Org Foundation
    X Server release:  11103000

Video Card:
    Driver:  NVIDIA Corporation GeForce GTX 460/PCIe/SSE2

    Driver Version:  4.3.0 NVIDIA 310.14
    Desktop Color Depth: 24 bits per pixel
    Monitor Refresh Rate: 59 Hz
    VendorID:  0x10de
    DeviceID:  0xe22
    Number of Monitors:  1
    Number of Logical Video Cards:  1
    Primary Display Resolution:  1680 x 1050
    Desktop Resolution: 1680 x 1050
    Primary Display Size: 18.62" x 11.65"  (21.93" diag)
                                            47.3cm x 29.6cm  (55.7cm diag)
    Primary Bus: PCI Express 16x
    Primary VRAM: 767 MB
    Supported MSAA Modes:  2x 4x 8x 16x 

Sound card:
    Audio device: Realtek ALC888

Memory:
    RAM:  4027 Mb

Miscellaneous:
    UI Language:  English
    LANG:  en_US.UTF-8
    Microphone:  Not set
    Total Hard Disk Space Available:  78487 Mb
    Largest Free Hard Disk Block:  17831 Mb

Installed software:

Recent Failure Reports:

I also had this happen after a while (all text looked fine at first). Gone after restarting HL1 and hasn't yet happened again.

system info