I have the above problem too, running 12.04 in VirtualBox. I installed the Ubuntu UI toolkit per the standard instructions. It happens with the standard 'Hello World' program provided in QT Creator too.
As requested, the (first part of) the output of glxinfo is:

name of display: :0
display: :0  screen: 0
direct rendering: Yes
server glx vendor string: Chromium
server glx version string: 1.3 Chromium
server glx extensions:
    GLX_ARB_multisample, GLX_EXT_texture_from_pixmap, GLX_SGIX_fbconfig, 
    GLX_ARB_get_proc_address
client glx vendor string: Chromium
client glx version string: 1.3 Chromium
client glx extensions:
    GLX_ARB_multisample, GLX_EXT_texture_from_pixmap, GLX_SGIX_fbconfig, 
    GLX_ARB_get_proc_address
GLX version: 1.3
GLX extensions:
    GLX_ARB_multisample, GLX_EXT_texture_from_pixmap, GLX_SGIX_fbconfig, 
    GLX_ARB_get_proc_address
OpenGL vendor string: Humper
OpenGL renderer string: Chromium
OpenGL version string: 2.1 Chromium 1.9
OpenGL shading language version string: 4.20
OpenGL extensions:
    GL_EXT_texture_compression_s3tc, GL_EXT_draw_range_elements, 
    GL_EXT_framebuffer_object, GL_EXT_compiled_vertex_array, 
    GL_ARB_depth_texture, GL_ARB_fragment_program, GL_ARB_multisample, 
    GL_ARB_multitexture, GL_ARB_occlusion_query, GL_ARB_point_parameters, 
    GL_ARB_point_sprite, GL_ARB_shadow, GL_ARB_shadow_ambient, 
    GL_ARB_texture_border_clamp, GL_ARB_texture_compression, 
    GL_ARB_texture_cube_map, GL_ARB_texture_env_add, 
    GL_ARB_texture_env_combine, GL_EXT_texture_env_combine, 
    GL_ARB_texture_env_crossbar, GL_ARB_texture_env_dot3, 
    GL_EXT_texture_env_dot3, GL_ARB_texture_mirrored_repeat, 
    GL_IBM_texture_mirrored_repeat, GL_ATI_texture_mirror_once, 
    GL_ARB_texture_non_power_of_two, GL_ARB_transpose_matrix, 
    GL_ARB_vertex_buffer_object, GL_ARB_pixel_buffer_object, 
    GL_ARB_vertex_program, GL_ARB_window_pos, GL_EXT_blend_color, 
    GL_EXT_blend_minmax, GL_EXT_blend_func_separate, GL_EXT_blend_subtract, 
    GL_EXT_texture_env_add, GL_EXT_fog_coord, GL_EXT_multi_draw_arrays, 
    GL_EXT_secondary_color, GL_EXT_shadow_funcs, GL_EXT_stencil_wrap, 
    GL_EXT_texture_cube_map, GL_EXT_texture_edge_clamp, 
    GL_EXT_texture_filter_anisotropic, GL_EXT_texture_lod_bias, 
    GL_EXT_texture_object, GL_EXT_texture3D, GL_NV_texgen_reflection, 
    GL_EXT_texture_rectangle, GL_ARB_texture_rectangle, 
    GL_SGIS_generate_mipmap, GL_SGIS_texture_edge_clamp, 
    GL_ARB_shading_language_100, GL_ARB_shader_objects, GL_ARB_vertex_shader, 
    GL_ARB_fragment_shader, GL_EXT_texture_sRGB, GL_EXT_framebuffer_blit, 
    GL_EXT_blend_equation_separate, GL_CR_state_parameter, 
    GL_CR_cursor_position, GL_CR_bounding_box, GL_CR_print_string, 
    GL_CR_tilesort_info, GL_CR_synchronization, GL_CR_head_spu_name, 
    GL_CR_performance_info, GL_CR_window_size, GL_CR_tile_info, 
    GL_CR_saveframe, GL_CR_readback_barrier_size, GL_CR_server_id_sharing, 
    GL_CR_server_matrix,  GL_EXT_stencil_two_side

96 GLX Visuals
    visual  x   bf lv rg d st  colorbuffer  sr ax dp st accumbuffer  ms  cav
  id dep cl sp  sz l  ci b ro  r  g  b  a F gb bf th cl  r  g  b  a ns b eat
----------------------------------------------------------------------------
0x021 24 tc  0  32  0 r  y y   8  8  8  8 .  .  0 16  8 16 16 16 16  0 0 None
0x0db 24 tc  0  32  0 r  y y   8  8  8  8 .  .  0 16  8 16 16 16 16  0 0 None
0x0dc 24 tc  0  32  0 r  y y   8  8  8  8 .  .  0 16  8 16 16 16 16  0 0 None
0x0dd 24 tc  0  32  0 r  y y   8  8  8  8 .  .  0 16  8 16 16 16 16  0 0 None
0x0de 24 tc  0  32  0 r  y y   8  8  8  8 .  .  0 16  8 16 16 16 16  0 0 None