Outlook 2003 hangs when composing mail

Suddenly my Outlook 2003 hangs intermitently when composing mail and sometimes I get messages saying it cannot use Word as the editor and must switch to using Outlook editor. I have used Word for years as editor. The box is still ticked under Tools to use Word.
I say hanging, it actually shows the teatimer symbol for a while and I have to wait for this to finish before being able to progress, this will happen intermitently while composing mail.
Also this happens sometimes when I am deleting mail.
All functions eventually complete, but are slowed significantly during the delays.

I thought I would run a scan to check for any virus using Malwarebytes, but it would not run and showed a Runtime error. So I tried to delete this program with the intent to re-download it, but in Add/Remove programs it also showed a Runtime error when I clicked delete. So I am not sure if there is any connection here between the two problems?

However the Outlook problem is my priority.
Help is requested with this please.

thanks
bar457