Sequence Numbers Jumping

We are migrating an application from Oracle 9 to Oracle 10. The 
application uses several sequence objects for user visible sequences. 
For some reason on Oracle 10 the sequences are jumping. I've checked 
that the sequences are defined as ordered and tried disabling the 
caching (a desperation measure as I don't believe it could be that).

Any suggestions as to what could be causing this in Oracle 10 when it 
did not occur in Oracle 9? Any suggestions as to how to investigate this 
as I am new to Oracle?
-- 
Flash Gordon