I have the same problem. I cant log in without SL crashing or my screen going black. I did what you suggeted. Here is my info:
CPU: Intel® Pentium® 4 CPU 2.80GHz (2793 MHz)
Memory: 3070 MB
OS Version: Microsoft Windows XP Service Pack 3 (Build 2600) compatibility mode. real ver: 6.0 (Build 2900)
Graphics Card Vendor: ATI Technologies Inc.
Graphics Card: RADEON 9100 DDR x86/SSE2
Windows Graphics Driver Version: 6.14.0010.6614
OpenGL Version: 1.3.1072 WinXP Release
libcurl Version: libcurl/7.21.1 OpenSSL/0.9.8j zlib/1.2.3 c-ares/1.7.1
J2C Decoder Version: KDU v6.4.1
Audio Driver Version: FMOD version 3.750000
Qt Webkit Version: 4.7.1 (version number hard-coded)
Voice Server Version: Not Connected
Built with MSVC version 1400
Can you help? Thanks so much!