Question : update table never ending

Hi Experts

i have a problem:
when i try to update a column of a specific table with no where clause, to update all rows,
the update is continue and never finish.
when i update 1 column with where by key- all fine.
the query: (very simple...)
update  karstoel.T_PlantItem set SP_AllowPublishFlag =1

what i did:
1. rebuild indexes - not help
2. build new index for the update column with the key column -  not help.
3. check if the table is locked - not locked.
4. delete the column and recreate it -not help
5. try to update another column - not help so the problem in table.

please help.

10x

Answer : update table never ending

Yes, this is the fact if you want to update 190,000 records in an average computer.