Few weeks ago, Pat has released an upgrade to the kernel-headers packages (just a recompilation since Pat has started to use CFQ for the I/O Scheduling in his current and future kernels included in Slackware-Current). Yesterday, he released an upgrade to XOrg Server packages and last night, i upgrade my packages using this version and eventually i had to reinstall my NVIdia driver (It never happened on my desktop before, only in my laptop). The reason might be because of the broken link, caused by the new packages, so in order to fix it, just simply reinstalling will be fine.
The problem comes when it started to build the kernel modules (Slackware is not included in the precompiled kernel interfaces in NVIdia driver), because i have just upgraded my kernel-headers (it's just a regeneration, but the NVidia driver didn't think about that), so finally i decided to upgrade my kernel to 184.108.40.206 to fix the problem (i was planning not to install this version, as 2.6.21 is very close to the final release and i'm waiting for this instead of the 220.127.116.11, but i guess it must be done. I also have a change to try the new CFQ I/O Scheduling and so far the result is good. I don't have any problem after i recompile the kernel with this new Scheduler). By the way, after the kernel upgrades, NVidia kernel works like charm, and everything is back to normal again.