Thread: Client.dll and engine.dll

hey everyone,
please i need to fix these problems.
When i start playing, after 10min it sents me back to desktop with an error problem.
Sometimes it's client.dll and sometimes it's engine.dll.

Problem signature
Problem Event Name: APPCRASH
Application Name: left4dead.exe
Application Version: 0.0.0.0
Application Timestamp: 491a4be1
Fault Module Name: engine.dll
Fault Module Version: 0.0.0.0
Fault Module Timestamp: 491b93ad
Exception Code: c0000005
Exception Offset: 002bfc5a
OS Version: 6.0.6001.2.1.0.768.3
Locale ID: 1033
Additional Information 1: fd00
Additional Information 2: ea6f5fe8924aaa756324d57f87834160
Additional Information 3: fd00
Additional Information 4: ea6f5fe8924aaa756324d57f87834160

Problem signature
Problem Event Name: APPCRASH
Application Name: left4dead.exe
Application Version: 0.0.0.0
Application Timestamp: 491a4be1
Fault Module Name: client.dll
Fault Module Version: 0.0.0.0
Fault Module Timestamp: 4921eb8f
Exception Code: c0000005
Exception Offset: 002e6ec4
OS Version: 6.0.6001.2.1.0.768.3
Locale ID: 1033
Additional Information 1: b886
Additional Information 2: f80dece8d36e49c8cd232de8e361356f
Additional Information 3: 5cc0
Additional Information 4: cddcbf9e9875f01ca637151e71c38401

My specs:
------------------
System Information
------------------
Operating System: Windows Vista™ Home Premium (6.0, Build 6001) Service Pack 1 (6001.vistasp1_gdr.090302-1506)
Language: English (Regional Setting: English)
System Manufacturer: Hewlett-Packard
System Model: HP Pavilion dv6700 Notebook PC
BIOS: Ver 1.00PARTTBL
Processor: Intel(R) Core(TM)2 Duo CPU T9300 @ 2.50GHz (2 CPUs), ~2.5GHz
Memory: 3070MB RAM
Page File: 1794MB used, 4545MB available
DirectX Version: DirectX 10

---------------
Display Devices
---------------
Card name: NVIDIA GeForce 8400M GS
Manufacturer: NVIDIA
Chip type: GeForce 8400M GS
Display Memory: 1521 MB
Dedicated Memory: 241 MB
Shared Memory: 1279 MB

thanks.

i re-installed it twice and still it didn't work