Currently we are receiving the following error in our database

'You have 2 tablespace(s) whose physical block reads are 1.5 times higher than their physical reads. You may wish to review the indexes for these tablespaces.'

Can anybody guide me what could be the possible error in indexes?

Problem no-2:

We are using Oracle 8.0.5 on NT server. Two days back suddenly Oracle start responding very slowly and on ivestigation, it was found that Oracle.EXE on server is using 99% of CPU due to which the users were unable to receive timely response.

We tried to find out the reason but could not succeeded. Pl. help.

Thanks in advance.