Fatal error when clicking the RTE buttons

Clicking the "Insert/edit link", "Insert/edit image" or "Edit HTML Source" buttons in the rich text editor when writing a new issue or editing an existing one gives me the following error:

Host:
local:9000
Error:
com.opensymphony.xwork2.config.ConfigurationException
Error Detail:
The Struts dispatcher cannot be found. This is usually caused by using Struts tags without the associated filter. Struts tags are only usable when the request has passed through its servlet filter, which initializes the Struts dispatcher needed for this tag. - [unknown location] at org.apache.struts2.views.jsp.TagUtils.getStack(TagUtils.java:59)
Java:
Sun Microsystems Inc.1.5.0_08C:\Program Files\Java\jdk1.5.0_08\jre
Machine:
Windows NT (unknown)x866.0
Browser:
Mozilla/5.0 (Windows; U; Windows NT 6.0; en-GB; rv:1.9.0.14) Gecko/2009082707 Firefox/3.0.14 (.NET CLR 3.5.30729)
fixx version:
1.8
Time:
Thu Oct 15 20:13:27 GMT 2009