Firstly I would check that you are applying the correct patch, there are US and Euro versions of the 1.05 patch.
http://patches.ubi.com/splinter_cell_chaos_theory/
splinter_cell_chaos_theory_1.00_To_1.05_euro.exe 18-Oct-2005 19:21 115M
The patching process does take a little while, as I recall it does seem as though it gets "stuck", maybe you just need to wait a little longer.