Which versions of Opus and TortoiseSVN are you using?
If you've just updated to TortoiseSVN 1.5 and had previously set its OwnerdrawnMenus to a non-default value then you'll need to change/delete the registry setting.
For some reason the meaning of TortoiseSVN's OwnerdrawnMenus setting changed in version 1.5. The values that used to make it work better in some programs now turn off icons completely. At least with Opus 9 and TortoiseSVN 1.5 you now get the best results if the OwnerdrawnMenus is deleted completely (which is the default).
If you're using Opus 8 then see this thread.