After Patch 5, StarCraft II just stopped launching. No errors whatsoever.
If I open the Task Manager and then launch SC2, the process StarCraft2.exe will show up for a few seconds and then disappear.

I also tried the following before posting here:
1) Re-installed - did this twice
2) Run as Administrator - no effect
3) Change all the permissions of files and folders of the SC2 installation folder - no effect
---- note: I then uninstalled and re-installed from hereon - so all settings/permissions are back, the second re-installation is still the same.

Here's my DxDiag:

--------------------------------------------------------------------------------------------------------------------------------------------
------------------
System Information
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Time of this report: 3/14/2010, 16:01:38
Machine name: HOME-DESKTOP01
Operating System: Windows 7 Ultimate 64-bit (6.1, Build 7600) (7600.win7_rtm.090713-1255)
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 CPU 6400 @ 2.13GHz (2 CPUs), ~2.1GHz
Memory: 2048MB RAM
Available OS Memory: 2046MB RAM
Page File: 1483MB used, 2609MB 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: 6.01.7600.16385 64bit Unicode

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DxDiag Notes
------------
Display Tab 1: No problems found.
Sound Tab 1: No problems found.
Sound Tab 2: No problems found.
Input Tab: No problems found.

--------------------
DirectX Debug Levels
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Direct3D: 0/4 (retail)
DirectDraw: 0/4 (retail)
DirectInput: 0/5 (retail)
DirectMusic: 0/5 (retail)
DirectPlay: 0/9 (retail)
DirectSound: 0/5 (retail)
DirectShow: 0/6 (retail)

---------------
Display Devices
---------------
Card name: NVIDIA GeForce 7300 LE
Manufacturer: NVIDIA
Chip type: GeForce 7300 LE
DAC type: Integrated RAMDAC
Device Key: Enum\PCI\VEN_10DE&DEV_01D1&SUBSYS_81F41043&REV_A1
Display Memory: 889 MB
Dedicated Memory: 121 MB
Shared Memory: 767 MB
Current Mode: 1280 x 1024 (32 bit) (60Hz)
Monitor Name: Generic PnP Monitor
Monitor Model: T713SH
Monitor Id: GSM4448
Native Mode: 1024 x 768(p) (84.997Hz)
Output Type: HD15
Driver Name: nvd3dumx.dll,nvd3dum
Driver File Version: 8.16.0011.9107 (English)
Driver Version: 8.16.11.9107
DDI Version: 9Ex
Driver Model: WDDM 1.0
Driver Attributes: Final Retail
Driver Date/Size: 9/27/2009 23:12:22, 9441384 bytes
WHQL Logo'd: Yes
WHQL Date Stamp:
Device Identifier: {D7B71E3E-4291-11CF-6050-FFA11EC2C535}
Vendor ID: 0x10DE
Device ID: 0x01D1
SubSys ID: 0x81F41043
Revision ID: 0x00A1
Driver Strong Name: oem2.inf:NVIDIA_SetB_Devices.NTamd64.6.0:Section001:8.16.11.9107:pci\ven_10de&dev_01d1
Rank Of Driver: 00E62001
Video Accel: ModeMPEG2_A ModeMPEG2_C ModeVC1_B ModeWMV9_B ModeVC1_A ModeWMV9_A
Deinterlace Caps: {6CB69578-7617-4637-91E5-1C02DB810285}: Format(In/Out)=(YUY2,YUY2) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_PixelAdaptive
{F9F19DA5-3B09-4B2F-9D89-C64753E3EAAB}: Format(In/Out)=(YUY2,YUY2) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(YUY2,YUY2) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY
{335AA36E-7884-43A4-9C91-7F87FAF3E37E}: Format(In/Out)=(YUY2,YUY2) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_BOBVerticalStretch
{6CB69578-7617-4637-91E5-1C02DB810285}: Format(In/Out)=(UYVY,UYVY) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY DeinterlaceTech_PixelAdaptive
{F9F19DA5-3B09-4B2F-9D89-C64753E3EAAB}: Format(In/Out)=(UYVY,UYVY) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY
{5A54A0C9-C7EC-4BD9-8EDE-F3C75DC4393B}: Format(In/Out)=(UYVY,UYVY) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_StretchX VideoProcess_StretchY
{335AA36E-7884-43A4-9C91-7F87FAF3E37E}: Format(In/Out)=(UYVY,UYVY) Frames(Prev/Fwd/Back)=(0,0,0) Caps=VideoProcess_YUV2RGB VideoProcess_Stretc

Yarso,

Can you try using Selective Startup to keep any background programs from loading with Windows?

Click Start and type MSCONFIG and press enter
Once the System Configuration utility loads, on the General tab check the box for Selective Startup, then uncheck the box for Load startup items (to undo this check the box for Normal Startup)
Click Apply and then OK to restart your computer