One: you are running a bit hot for a desktop. 48 C. Should be down around 35 C. Make sure the vents are clear and it is not standing in the sun or near a heat source. Shutdown but leave it plugged in. Remove the cover. Vacuum out the dust. Pay special attention to the CPU heatsink (you may need to remove the fan to get to clean it but usually it's just 4 screws and you can sat it aside.) Also clean the power supply intakes and fan. Turn on the PC and verify that the CPU and power supply fans start up quickly and run strongly without strange noises.
Then run speccy. On its front page it will tell you the CPU temperature. Run an anti-virus scan and monitor the temperature. It may climb a little but it should not change a lot.
Two: Your DVD-CD is not working correctly. I'm hoping its a filter problem:
1. Click Start, and then click Run.
2. In the Open box, type regedit, and then click OK.
3. In the navigation pane, locate and then click the following registry subkey:
4. In the right pane, click UpperFilters.
Note You may also see an UpperFilters.bak registry entry. You do not have to remove that entry. Click UpperFilters only. If you do not see the UpperFilters registry entry, you still might have to remove the LowerFilters registry entry. To do this, go to step 7.
5. On the Edit menu, click Delete.
6. When you are prompted to confirm the deletion, click Yes.
7. In the right pane, click LowerFilters.
Note If you do not see the LowerFilters registry entry, unfortunately this content cannot help you any further.
8. On the Edit menu, click Delete.
9. When you are prompted to confirm the deletion, click Yes.
10. Exit Registry Editor.
11. Restart the computer.