Back on Friday, July 18th we reported that Microsoft had released an updated version of the performance trace visualization tool BootVis. As you may remember this new version resolves a compatibility issue when running on Intel Pentium 4 processors with Hyperthreading technology enabled and an issue when using third-party IDE drivers. To benefit from the new version however users running Intel based Hyperthreading technology setups require a Windows XP kernel hot fix in order to correct a problem with BootVis tracing. It's here now. Important Note: This hotfix does NOT supersede Q820128: Windows XP Kernel Rollup Hotfix Package which includes additional files. Users that wish to be completely updated on the kernel, need to download both the kernel roll-up package and THEN this update. Warp2Search is not responsible for possible damage done to software or hardware after applying this patch. Download at your own risk. The Q821581 kernel hotfix contains the following system files: Date Time Version Size File name --------------------------------------------------------------------- 29-May-2003 11:03 5.1.2600.1228 1,896,448 Ntkrnlmp.exe with SP1 29-May-2003 11:03 5.1.2600.1228 1,952,256 Ntkrnlpa.exe with SP1 29-May-2003 11:03 5.1.2600.1228 1,924,096 Ntkrpamp.exe with SP1 29-May-2003 11:03 5.1.2600.1228 1,928,832 Ntoskrnl.exe with SP1 At the time of posting Microsoft has not yet released a knowledge base article for Q821581. It's likely that the hotfix contains more fixes than just Hyperthreading compatibility with BootVis 1.3.37. Download