Comment 2 for bug 619578

Same problem here with nvidia Geforce FX 5500 after updating to KDE 4.5. When enabling Composite and OpenGL X start to blink. Before updating composite worked flawlessly.

When Compositing disabled, the problem disappears.

$glxinfo

ame of display: :0.0
display: :0 screen: 0
direct rendering: Yes
server glx vendor string: NVIDIA Corporation
server glx version string: 1.4
server glx extensions:
    GLX_EXT_visual_info, GLX_EXT_visual_rating, GLX_SGIX_fbconfig,
    GLX_SGIX_pbuffer, GLX_SGI_video_sync, GLX_SGI_swap_control,
    GLX_EXT_texture_from_pixmap, GLX_ARB_multisample, GLX_NV_float_buffer
client glx vendor string: NVIDIA Corporation
client glx version string: 1.4
client glx extensions:
    GLX_ARB_get_proc_address, GLX_ARB_multisample, GLX_EXT_visual_info,
    GLX_EXT_visual_rating, GLX_EXT_import_context, GLX_SGI_video_sync,
    GLX_NV_swap_group, GLX_NV_video_out, GLX_SGIX_fbconfig, GLX_SGIX_pbuffer,
    GLX_SGI_swap_control, GLX_NV_float_buffer, GLX_ARB_fbconfig_float,
    GLX_EXT_fbconfig_packed_float, GLX_EXT_texture_from_pixmap,
    GLX_EXT_framebuffer_sRGB, GLX_NV_present_video
GLX version: 1.3
GLX extensions:
    GLX_EXT_visual_info, GLX_EXT_visual_rating, GLX_SGIX_fbconfig,
    GLX_SGIX_pbuffer, GLX_SGI_video_sync, GLX_SGI_swap_control,
    GLX_EXT_texture_from_pixmap, GLX_ARB_multisample, GLX_NV_float_buffer,
    GLX_ARB_get_proc_address
OpenGL vendor string: NVIDIA Corporation
OpenGL renderer string: GeForce FX 5500/AGP/SSE2
OpenGL version string: 2.1.2 NVIDIA 173.14.27
OpenGL shading language version string: 1.20 NVIDIA via Cg compiler
OpenGL extensions:

.xsession-errors