dasBlog is great, but it uses an older version of the nice freeTextbox to edit the posts.
This little editor provides great enhancments for editing and formatting, and IE8 is known from Version 3.2.0, but thats not the version we are using in dasBlog.
Luckily IE8 has a 'Compatibility View' setting, which defines a list of websites that will receive the old (IE7) user-agent string.
Image: Tools->Compatibility View Settings
If you own the website, you can set the compat mode using a meta-tag:
<meta http-equiv="X-UA-Compatible" content="IE=7" />