Hi guys, i have exactly the same problem with my HP dv4-2080br with Intel Core I5 and Radeon Mobility 4550:

lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation Core Processor Integrated Graphics Controller (rev 02)
01:00.0 VGA compatible controller: ATI Technologies Inc M93 [Mobility Radeon HD 4500 Series]

/var/log/Xorg.log

(II) Loading extension DRI2 
(II) LoadModule: "fglrx" 
(II) Loading /usr/lib/xorg/extra-modules/modules/drivers/fglrx_drv.so 
(II) Module fglrx: vendor="FireGL - ATI Technologies Inc." 
    compiled for 1.7.1, module version = 8.72.11 
    Module class: X.Org Video Driver 
(II) Loading sub module "fglrxdrm" 
(II) LoadModule: "fglrxdrm" 
(II) Loading /usr/lib/xorg/extra-modules/modules/linux/libfglrxdrm.so 
(II) Module fglrxdrm: vendor="FireGL - ATI Technologies Inc." 
    compiled for 1.7.1, module version = 8.72.11 
(II) ATI Proprietary Linux Driver Version Identifier:8.72.11 
(II) ATI Proprietary Linux Driver Release Identifier: 8.723.1                   
            
(II) ATI Proprietary Linux Driver Build Date: Apr  8 2010 21:40:58 
(II) Primary Device is: PCI 0...@00:02:0 
(WW) Falling back to old probe method for fglrx 
(II) Loading PCS database from /etc/ati/amdpcsdb 
(--) Chipset Supported AMD Graphics Processor (0x9555) found 
(WW) fglrx: No matching Device section for instance (BusID PCI:0...@1:0:1) 
found 
(II) AMD Video driver is running on a device belonging to a group targeted for 
this release 
(II) AMD Video driver is signed 
(II) fglrx(0): pEnt->device->identifier=0x1a855e0 
(II) fglrx(0): === [atiddxPreInit] === begin 
(II) Loading sub module "vgahw" 
(II) LoadModule: "vgahw" 
(II) Loading /usr/lib/xorg/modules/libvgahw.so 
(II) Module vgahw: vendor="X.Org Foundation" 
    compiled for 1.7.6, module version = 0.1.0 
    ABI class: X.Org Video Driver, version 6.0 
(**) fglrx(0): Depth 24, (--) framebuffer bpp 32 
(II) fglrx(0): Pixel depth = 24 bits stored in 4 bytes (32 bpp pixmaps) 
(==) fglrx(0): Default visual is TrueColor 
(**) fglrx(0): Option "DPMS" "true" 
(==) fglrx(0): RGB weight 888 
(II) fglrx(0): Using 8 bits per RGB  
(==) fglrx(0): Buffer Tiling is ON 
(II) Loading sub module "fglrxdrm" 
(II) LoadModule: "fglrxdrm" 
(II) Reloading /usr/lib/xorg/extra-modules/modules/linux/libfglrxdrm.so 
ukiDynamicMajor: found major device number 250 
ukiDynamicMajor: found major device number 250 
ukiOpenByBusid: Searching for BusID PCI:1:0:0 
ukiOpenDevice: node name is /dev/ati/card0 
ukiOpenDevice: open result is 11, (OK) 
ukiOpenByBusid: ukiOpenMinor returns 11 
ukiOpenByBusid: ukiGetBusid reports PCI:1:0:0 
(--) fglrx(0): Chipset: "ATI Mobility Radeon HD 4500 Series " (Chipset = 
0x9555) 
(--) fglrx(0): (PciSubVendor = 0x103c, PciSubDevice = 0x1409) 
(==) fglrx(0): board vendor info: third party graphics adapter - NOT original 
ATI 
(--) fglrx(0): Linear framebuffer (phys) at 0xc0000000 
(--) fglrx(0): MMIO registers at 0xe8400000 
(--) fglrx(0): I/O port at 0x00006000 
(==) fglrx(0): ROM-BIOS at 0x000c0000 
(II) fglrx(0): AC Adapter is used 
(II) fglrx(0): Bad V_BIOS checksum 
(II) fglrx(0): Primary V_BIOS segment is: 0xc000 
(II) fglrx(0): Invalid ATI BIOS from int10, the adapter is not VGA-enabled 
(EE) fglrx(0): Invalid video BIOS signature! 
(EE) fglrx(0): GetBIOSParameter failed 
(EE) fglrx(0): PreInitAdatper failed 
(EE) fglrx(0): PreInit failed 
(II) fglrx(0): === [atiddxPreInit] === end 
(II) UnloadModule: "fglrx" 
(II) UnloadModule: "fglrxdrm" 
(II) UnloadModule: "vgahw" 
(II) Unloading /usr/lib/xorg/modules/libvgahw.so 
(II) UnloadModule: "fglrxdrm" 
(EE) Screen(s) found, but none have a usable configuration. 

Fatal server error: 
no screens found